util: always replace g_fsync usage with our wrapper

g_fsync was introduced in 2.63 which is newer than our minimum
glib version. A future commit will introduce compile time
checking of API versions to prevent accidental usage of APIs
from glib newer than our min declared.

To avoid triggering this warning, however, we need to ensure
that we always use our wrapper function via glibcompat.c,
which will disable the API version warnings.
Reviewed-by: NPavel Hrdina <phrdina@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/util/glibcompat.c

@@ -55,6 +55,7 @@ vir_g_strdup_vprintf(const char *msg, va_list args)
 }
 
 
+/* Drop when min glib >= 2.63.0 */
 gint
 vir_g_fsync(gint fd)
 {

src/util/glibcompat.h

@@ -32,6 +32,5 @@ gint vir_g_fsync(gint fd);
 # define g_strdup_vprintf vir_g_strdup_vprintf
 #endif
 
-#if !GLIB_CHECK_VERSION(2, 63, 0)
-# define g_fsync vir_g_fsync
-#endif
+#undef g_fsync
+#define g_fsync vir_g_fsync