Revert spawnvp param cast and use no-incompatible-pointer-types in build-tcc.bat

tcc.c

@@ -132,7 +132,7 @@ static void help(void)
 #include <process.h>
 static int execvp_win32(const char *prog, char **argv)
 {
-    int ret = spawnvp(P_NOWAIT, prog, (char *const*)argv);
+    int ret = spawnvp(P_NOWAIT, prog, (const char *const*)argv);
     if (-1 == ret)
         return ret;
     cwait(&ret, ret, WAIT_CHILD);