PR11834: Use macros which are defined on Windows. Patch by Marina Yatsina.

llvm-svn: 149294
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
index 5a3fc58..4db1e2f 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
@@ -331,7 +331,8 @@
 
   std::string CPUName = CPU;
   if (CPUName.empty()) {
-#if defined (__x86_64__) || defined(__i386__)
+#if defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)\
+    || defined(__x86_64__) || defined(_M_AMD64) || defined (_M_X64)
     CPUName = sys::getHostCPUName();
 #else
     CPUName = "generic";