fixes for gcc 4.x

diff --git a/libasn1fix/asn1fix_cstring.c b/libasn1fix/asn1fix_cstring.c
index 215336b..f4e7604 100644
--- a/libasn1fix/asn1fix_cstring.c
+++ b/libasn1fix/asn1fix_cstring.c
@@ -13,7 +13,7 @@
 
 	if(expr->value && expr->value->type == ATV_STRING) {
 		struct _cstring_pattern cp;
-		char *buf = expr->value->value.string.buf;
+		char *buf = (char *)expr->value->value.string.buf;
 		int buflen = expr->value->value.string.size;
 		int start = 0;