Change type from char* to const char*

This is to gets rid of the explicit type conversation every iteration of the
loop.

Author: sourrust

src/util.c

@@ -28,9 +28,9 @@ void laco_kill(LacoState* laco, int status, const char* message) {
 
 bool laco_is_match(const char** matches, const char* test_string) {
   int i;
-  char* match;
+  const char* match;
 
-  for(i = 0; (match = (char*) matches[i]); i++) {
+  for(i = 0; (match = matches[i]); i++) {
     if(strcmp(test_string, match) == 0) {
       return true;
     }