re PR libstdc++/51181 (libstdc++.so __sync_sub_and_fetch_4 linkage error causing…

re PR libstdc++/51181 (libstdc++.so __sync_sub_and_fetch_4 linkage error causing many test suite failures on m68k-linux)

PR libstdc++/51181
        * libsupc++/eh_tm.cc (free_any_cxa_exception): Protect the use
        of __sync_sub_and_fetch with _GLIBCXX_ATOMIC_BUILTINS_4.

From-SVN: r181465

libstdc++-v3/ChangeLog

+2011-11-17  Richard Henderson  <rth@redhat.com>
+
+	PR libstdc++/51181
+	* libsupc++/eh_tm.cc (free_any_cxa_exception): Protect the use
+	of __sync_sub_and_fetch with _GLIBCXX_ATOMIC_BUILTINS_4.
+
 2011-11-18  Jonathan Wakely  <jwakely.gcc@gmail.com>
 
 	* testsuite/30_threads/thread/native_handle/typesizes.cc: Do not run

libstdc++-v3/libsupc++/eh_tm.cc

@@ -45,7 +45,9 @@ free_any_cxa_exception (_Unwind_Exception *eo)
       __cxa_free_dependent_exception (dep);
     }
 
+#ifdef _GLIBCXX_ATOMIC_BUILTINS_4
   if (__sync_sub_and_fetch (&h->referenceCount, 1) == 0)
+#endif
     __cxa_free_exception (h + 1);
 }