Makefiles: don't use -xobjective-c when linking files on Mac

Last commit caused -xobjective-c to be passed during linking on
Mac, causing object files to be treated as source files.  Add a
-xnone flag to AM_LDFLAGS, canceling the effect of -xobjective-c.

Additinally, add a -xobjective-c++ flag to AM_CXXFLAGS, so that we
can use Objective-C in C++ files on Mac, if we ever need to.

app-tools/Makefile.am

@@ -7,6 +7,8 @@ libappwidgets = $(top_builddir)/app/widgets/libappwidgets.a
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 endif
 
 if OS_WIN32
@@ -71,3 +73,9 @@ AM_CPPFLAGS = \
 
 AM_CFLAGS = \
 	$(xobjective_c)
+
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)

app/core/Makefile.am

@@ -2,6 +2,8 @@
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 endif
 
 AM_CPPFLAGS = \
@@ -23,6 +25,12 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	$(xobjective_c)
 
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
 noinst_LIBRARIES = libappcore.a
 
 libappcore_a_sources = \

app/display/Makefile.am

@@ -2,6 +2,8 @@
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 endif
 
 AM_CPPFLAGS = \
@@ -17,6 +19,12 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	$(xobjective_c)
 
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
 noinst_LIBRARIES = libappdisplay.a
 
 libappdisplay_a_sources = \

app/gui/Makefile.am

@@ -2,6 +2,8 @@
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 endif
 
 AM_CPPFLAGS = \
@@ -21,6 +23,12 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	$(xobjective_c)
 
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
 noinst_LIBRARIES = libappgui.a
 
 libappgui_a_sources = \

app/widgets/Makefile.am

@@ -2,6 +2,8 @@
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 endif
 
 AM_CPPFLAGS = \
@@ -19,6 +21,12 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	$(xobjective_c)
 
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
 noinst_LIBRARIES = libappwidgets.a
 
 libappwidgets_a_sources = \

libgimp/Makefile.am

@@ -13,6 +13,8 @@ endif
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 framework_cocoa = -framework Cocoa
 endif
 
@@ -80,6 +82,12 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	$(xobjective_c)
 
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
 lib_LTLIBRARIES = libgimp-@GIMP_API_VERSION@.la libgimpui-@GIMP_API_VERSION@.la
 
 PDB_WRAPPERS_C = \
@@ -395,7 +403,8 @@ libgimp_@GIMP_API_VERSION@_la_LDFLAGS = \
 	-version-info $(LT_VERSION_INFO)	\
 	$(no_undefined)				\
 	$(libgimp_export_symbols)		\
-	$(framework_cocoa)
+	$(framework_cocoa)			\
+	$(xnone)
 
 EXTRA_libgimp_@GIMP_API_VERSION@_la_DEPENDENCIES = $(gimp_def)
 
@@ -413,7 +422,8 @@ libgimpui_@GIMP_API_VERSION@_la_LDFLAGS = \
 	-version-info $(LT_VERSION_INFO)	\
 	$(no_undefined)				\
 	$(libgimpui_export_symbols)		\
-	$(framework_cocoa)
+	$(framework_cocoa)			\
+	$(xnone)
 
 EXTRA_libgimpui_@GIMP_API_VERSION@_la_DEPENDENCIES = $(gimpui_def)
 

libgimpbase/Makefile.am

@@ -6,6 +6,8 @@ endif
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 framework_cocoa = -framework Cocoa
 endif
 
@@ -69,10 +71,16 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	$(xobjective_c)
 
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
 AM_CCASFLAGS = \
 	-I$(top_builddir)	\
 	-I$(top_srcdir)
 
+AM_LDFLAGS = \
+	$(xnone)
+
 EXTRA_DIST = \
 	gimpbase.def
 
@@ -165,7 +173,8 @@ libgimpbase_@GIMP_API_VERSION@_la_LDFLAGS = \
 	-version-info $(LT_VERSION_INFO)	\
 	$(no_undefined) 			\
 	$(libgimpbase_export_symbols)		\
-	$(framework_cocoa)
+	$(framework_cocoa)			\
+	$(xnone)
 
 EXTRA_libgimpbase_@GIMP_API_VERSION@_la_DEPENDENCIES = $(gimpbase_def)
 

libgimpthumb/Makefile.am

@@ -6,6 +6,8 @@ endif
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 framework_cocoa = -framework Cocoa
 endif
 
@@ -55,6 +57,12 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	$(xobjective_c)
 
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
 EXTRA_DIST = \
 	gimpthumb.def
 
@@ -84,7 +92,8 @@ libgimpthumb_@GIMP_API_VERSION@_la_LDFLAGS = \
 	-version-info $(LT_VERSION_INFO)	\
 	$(no_undefined)				\
 	$(libgimpthumb_export_symbols)		\
-	$(framework_cocoa)
+	$(framework_cocoa)			\
+	$(xnone)
 
 libgimpthumb_@GIMP_API_VERSION@_la_LIBADD = \
 	$(GDK_PIXBUF_LIBS)	\

libgimpwidgets/Makefile.am

@@ -13,6 +13,8 @@ endif
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 framework_cocoa = -framework Cocoa
 endif
 
@@ -63,6 +65,12 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	$(xobjective_c)
 
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
 lib_LTLIBRARIES = libgimpwidgets-@GIMP_API_VERSION@.la
 
 libgimpwidgets_sources = \
@@ -270,7 +278,8 @@ libgimpwidgets_@GIMP_API_VERSION@_la_LDFLAGS = \
 	-version-info $(LT_VERSION_INFO)	\
 	$(no_undefined) 			\
 	$(libgimpwidgets_export_symbols)	\
-	$(framework_cocoa)
+	$(framework_cocoa)			\
+	$(xnone)
 
 EXTRA_libgimpwidgets_@GIMP_API_VERSION@_la_DEPENDENCIES = $(gimpwidgets_def)
 

plug-ins/script-fu/Makefile.am

@@ -2,6 +2,8 @@
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 framework_cocoa = -framework Cocoa
 endif
 
@@ -28,21 +30,25 @@ include $(top_srcdir)/build/windows/gimprc-plug-ins.rule
 script_fu_RC = script-fu.rc.o
 endif
 
-AM_CFLAGS = \
-	-DSTANDALONE=0		\
-	-DUSE_INTERFACE=1	\
-	-DUSE_STRLWR=0		\
-	$(xobjective_c)
-
 AM_CPPFLAGS = \
 	-I$(top_srcdir)		\
 	$(GTK_CFLAGS)		\
 	$(GEGL_CFLAGS)		\
-	-I$(includedir)
+	-I$(includedir)		\
+	-DSTANDALONE=0		\
+	-DUSE_INTERFACE=1	\
+	-DUSE_STRLWR=0
+
+AM_CFLAGS = \
+	$(xobjective_c)
+
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
 
 AM_LDFLAGS = \
 	$(mwindows)		\
-	$(framework_cocoa)
+	$(framework_cocoa)	\
+	$(xnone)
 
 SUBDIRS = tinyscheme ftx scripts
 

tools/Makefile.am

@@ -6,6 +6,8 @@ libgimpbase = $(top_builddir)/libgimpbase/libgimpbase-$(GIMP_API_VERSION).la
 
 if PLATFORM_OSX
 xobjective_c = "-xobjective-c"
+xobjective_cxx = "-xobjective-c++"
+xnone = "-xnone"
 endif
 
 if OS_WIN32
@@ -92,6 +94,12 @@ AM_CPPFLAGS = \
 AM_CFLAGS = \
 	$(xobjective_c)
 
+AM_CXXFLAGS = \
+	$(xobjective_cxx)
+
+AM_LDFLAGS = \
+	$(xnone)
+
 EXTRA_DIST = \
 	defcheck.py	\
 	gimp-mkenums	\