Change main C snippet to an array of const char*

UltiSnips/c.snippets

@@ -157,7 +157,7 @@ default: {
 endsnippet
 
 snippet main "Main function stub"
-int main(${1:int argc, char **argv}) {
+int main(${1:int argc, const char* argv[]}) {
 	$0
 }
 endsnippet