There where some problems (??) with ccache not detecting changes during meson
checks. Setting CCACHE_DISABLE during the meson execution makes ccache not use
the cache and pass things directly to the compiler.
Turns out that GCC errors out when building the GLib test suite, as it
now checks for overflows in allocator functions, and we're testing for
those.
This would not be an issue for GTK, but since we're building GLib as a
subproject, we get failures for those as well.
Until we can find out how to disable errors for subprojects, or fix the
GLib test suite not to trip up warnings in GCC, we're going to live
without compiler warnings treated as errors for a while.
xvfb doesn't like C.utf8 and returns XLocaleNotSupported.
While (afaik) C.utf8 and C.UTF.8 should be the same thing, and the former
is returned by locale -a on Fedora, switch to C.UTF-8 to make xvfb happy.
This makes gtk+:gdk tests pass.
