validate: uses glib 2.56 API g_file_new_build_filename
g_file_new_build_filename() was added in glib 2.56 yet the meson build only checks for at least 2.44. Either the glib version check needs increasing, g_file_new_build_filename needs ifdef-ing, or replacing.
Linking error:
path/to/gst-build/build/../subprojects/gst-devtools/validate/gst/validate/gst-validate-utils.c:773: undefined reference to `g_file_new_build_filename'