Fix "'x' might be used uninitialized in this function" warnings.

tests/libtest/lib505.c

@@ -38,7 +38,7 @@
 int test(char *URL)
 {
   CURL *curl;
-  CURLcode res;
+  CURLcode res = CURLE_OK;
   FILE *hd_src ;
   int hd ;
   struct_stat file_info;

tests/libtest/lib507.c

@@ -5,7 +5,7 @@ int test(char *URL)
   CURL* curls;
   CURLM* multi;
   int still_running;
-  int i;
+  int i = -1;
   CURLMsg *msg;
 
   multi = curl_multi_init();