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.

llvm-svn: 187956
diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 7d9382e..cf70ad6 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -776,6 +776,9 @@
   if (Kind.isThreadLocal())
     return getTLSDataSection();
 
+  if (Kind.isReadOnly() && ReadOnlySection != 0)
+    return ReadOnlySection;
+
   return getDataSection();
 }