In 9236ee0564 the cups code was updated to use newer API with cups >= 2
and a later commit (a7e207abe) dropped the old code paths and added version
checks in meson/autotools.
The newly used functions were httpConnect2 and httpReconnect2 which are
available since 1.7 and don't require cups 2.0.
Change the versions checks to 1.7 instead so gtk can still be build with
older cups (macOS 10.9 for example, see #1950)
d402cd4e2e