Don't include alloca.h.

diff --git a/tools/wrc/parser.y b/tools/wrc/parser.y
index 3205344..26593b1 100644
--- a/tools/wrc/parser.y
+++ b/tools/wrc/parser.y
@@ -91,7 +91,6 @@
 #include <assert.h>
 #include <ctype.h>
 #include <string.h>
-#include <alloca.h>
 
 #include <config.h>
 #include "wrc.h"