[locale] Reduce warnings for gcount()

- The read is at most sizeof(arr), so int is fine. Do
   the cast explicitly.

src/modules/locale/test_geoip.cpp

@@ -55,7 +55,7 @@ int main(int argc, char** argv)
     while( !std::cin.eof() ) {
         char arr[1024];
         std::cin.read(arr, sizeof(arr));
-        int s = std::cin.gcount();
+        int s = static_cast<int>( std::cin.gcount() );
         ba.append(arr, s);
     }