Revert "coff also doesn't have a ReadOnlySection yet, (!)"

This reverts commit r77814.

We were sticking global constants in the .data section instead of in the
.rdata section when emitting for COFF.

This fixes PR16831.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187956 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -776,6 +776,9 @@ SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
   if (Kind.isThreadLocal())
     return getTLSDataSection();
 
+  if (Kind.isReadOnly() && ReadOnlySection != 0)
+    return ReadOnlySection;
+
   return getDataSection();
 }