* src/system.h: Include alloca.h.

* src/main.c (main) [C_ALLOCA]: Call alloca (0).

src/system.h

@@ -79,6 +79,21 @@
 extern int errno;
 #endif
 
+/* AIX requires this to be the first thing in the file.  */
+#ifndef __GNUC__
+# if HAVE_ALLOCA_H
+#  include <alloca.h>
+# else
+#  ifdef _AIX
+ #pragma alloca
+#  else
+#   ifndef alloca /* predefined by HP cc +Olibcalls */
+char *alloca ();
+#   endif
+#  endif
+# endif
+#endif
+
 #if PROTOTYPES
 # define PARAMS(p) p
 #else