Try to unbreak the mingw32 build.

llvm-svn: 200973
diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
index 16e4092..62b6da0 100644
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -363,7 +363,7 @@
 
 unsigned Process::GetRandomNumber() {
   unsigned int result;
-  const errno_t ec = rand_s(&result);
+  const int ec = rand_s(&result);
   assert(ec == 0 && "rand_s failed");
   return result;
 }