Guard against the POSIX allowed behavior where access (file, X_OK)

Guard against the POSIX allowed behavior where access (file, X_OK)

Sun Dec  8 23:36:12 2002  Owen Taylor  <otaylor@redhat.com>

        * glib/gfileutils.c (g_file_test): Guard against
        the POSIX allowed behavior where access (file, X_OK)
        succeeds for uid==0 when no executable bits are set.

        * glib/gfileutils.c (g_file_test): Add doc notes
        about the possibility of race conditions, and the
        fact that EXISTS and IS_EXECUTABLE give results
        for the real uid not the effective user ID.
        (#81854, Morten Welinder.)