(NULL): Define only if not already defined.

diff --git a/src/alloca.c b/src/alloca.c
index 12c1122..31fb4e0 100644 (file)
--- a/src/alloca.c
+++ b/src/alloca.c
@@ -73,7 +73,9 @@ typedef void *pointer;
 typedef char *pointer;
 #endif
 
+#ifndef NULL
 #define        NULL    0
+#endif
 
 /* Different portions of Emacs need to call different versions of
    malloc.  The Emacs executable needs alloca to call xmalloc, because