Enable StackMap Serialization for COFF

Summary

This change turns on the emission of 
__LLVM_Stackmaps section when generating COFF binaries.

Test Plan

Added a scenario to the test case: 
test\CodeGen\X86\statepoint-stackmap-format.ll.

Code Review:

http://reviews.llvm.org/D10680



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240613 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCObjectFileInfo.cpp

@@ -733,6 +733,11 @@ void MCObjectFileInfo::initCOFFMCObjectFileInfo(Triple T) {
       ".tls$", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
                    COFF::IMAGE_SCN_MEM_WRITE,
       SectionKind::getDataRel());
+	  
+  StackMapSection = Ctx->getCOFFSection(".llvm_stackmaps",
+                                        COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
+                                            COFF::IMAGE_SCN_MEM_READ,
+                                        SectionKind::getReadOnly());	
 }
 
 void MCObjectFileInfo::InitMCObjectFileInfo(const Triple &TheTriple,