tests: Test that we can include all headers with an old MAX_VERSION

In principle we could script this so that each max-version.c is compiled
26 times, once per possible MAX_VERSION, but I haven't implemented
that here: just pinning to the oldest possible version is sufficient to
reproduce #2796.

These aren't included in the installed-tests, since they don't really
do anything at runtime (the important thing is that they compile
without warnings).

Reproduces: #2796
Signed-off-by: Simon McVittie <smcv@collabora.com>

gio/tests/meson.build

@@ -84,6 +84,7 @@ gio_tests = {
   },
   'inet-address' : {},
   'io-stream' : {},
+  'max-version' : {'install' : false},
   'memory-input-stream' : {},
   'memory-monitor' : {},
   'memory-output-stream' : {},