SwiftMix: Get rid of pointer types mismatch warning

Tests/SwiftMix/CMain.c

@@ -1,5 +1,5 @@
-extern int ObjCMain(int argc, char const* const argv[]);
-int main(int argc, char* argv[])
+extern int ObjCMain(void);
+int main(void)
 {
-  return ObjCMain(argc, argv);
+  return ObjCMain();
 }

Tests/SwiftMix/ObjCMain.m

@@ -1,4 +1,4 @@
 #import "SwiftMix-Swift.h"
-int ObjCMain(int argc, char const* const argv[]) {
+int ObjCMain(void) {
   return [SwiftMainClass SwiftMain];
 }