Actually check the version constraint when looking for the glib
dependency.
The version check will make meson use the fallback dependency when the
one from the system is not recent enough, and eventually make the build
succeed even on some older systems like Ubuntu 16.04.
Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-editing-services/-/merge_requests/212>
gstvalidate_dep = dependency('gst-validate-1.0', version : gst_req, required : get_option('validate'),
fallback : ['gst-devtools', 'validate_dep'])
-gio_dep = dependency('gio-2.0', fallback: ['glib', 'libgio_dep'])
+gio_dep = dependency('gio-2.0', version: glib_req, fallback: ['glib', 'libgio_dep'])
libxml_dep = dependency('libxml-2.0', required: get_option('xptv'))
cdata.set('DISABLE_XPTV', not libxml_dep.found())