Comment 7 for bug 1916705

> Also open-vm-tools is also FTBFS by this, so I need to add a task and work on that as well.

You want this kind of thing minimally to get over the FTBFS:

--- open-vm-tools-11.2.5.orig/open-vm-tools/configure.ac
+++ open-vm-tools-11.2.5/open-vm-tools/configure.ac
@@ -503,6 +503,9 @@ AC_CHECK_PROG([have_genmarshal],
               [yes],
               [no])

+AC_DEFINE(GLIB_VERSION_MIN_REQUIRED, GLIB_VERSION_2_34, [Ignore post 2.34 deprecations])
+AC_DEFINE(GLIB_VERSION_MAX_ALLOWED, GLIB_VERSION_2_34, [Prevent post 2.34 APIs])
+
 if test "$have_genmarshal" != "yes"; then
    AC_MSG_ERROR([glib-genmarshal is required; make sure it is available in your path.])
 fi

But I would recommend also at least asking upstream to do the full fix and move glib's headers out of 'extern "C"' too as outlined in comment #2 here.