llvm-stub.cpp: mingw-w64 tweak.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128205 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/llvm-stub/llvm-stub.c b/tools/llvm-stub/llvm-stub.c
index 31c2d09..69cd6ed 100644
--- a/tools/llvm-stub/llvm-stub.c
+++ b/tools/llvm-stub/llvm-stub.c
@@ -64,7 +64,7 @@
   memcpy((char **)Args+2, argv+1, sizeof(char*)*argc);
 
   /* Run the JIT. */
-#ifndef _WIN32
+#if !defined(_WIN32) || defined(__MINGW64__)
   execvp(Interp, (char **)Args); /* POSIX execvp takes a char *const[]. */
 #else
   execvp(Interp, Args); /* windows execvp takes a const char *const *. */