old krb4 fix for strlcat() prototype

lib/strequal.h

@@ -32,4 +32,8 @@ int curl_strnequal(const char *first, const char *second, size_t max);
 #define strequal(a,b) curl_strequal(a,b)
 #define strnequal(a,b,c) curl_strnequal(a,b,c)
 
+#ifndef HAVE_STRLCAT
+size_t strlcat(char *dst, const char *src, size_t siz);
+#endif
+
 #endif