(alloca) [__GNUC__]: Define only if not already defined.

diff --git a/src/sys2.h b/src/sys2.h
index c29a98139d055a9df74b50d8299c9be9389c8634..513b837d8b1acdd7830950a728cabd063d953fa0 100644 (file)
--- a/src/sys2.h
+++ b/src/sys2.h
@@ -142,7 +142,9 @@
 #endif
 
 #if __GNUC__
-# define alloca __builtin_alloca
+# ifndef alloca
+#  define alloca __builtin_alloca
+# endif
 #else
 # if HAVE_ALLOCA_H
 #  include <alloca.h>