make isVirtualSection a virtual method on MCSection. Chris' suggestion.

llvm-svn: 119547
diff --git a/llvm/lib/MC/MCSectionCOFF.cpp b/llvm/lib/MC/MCSectionCOFF.cpp
index 0909df4..90091f0 100644
--- a/llvm/lib/MC/MCSectionCOFF.cpp
+++ b/llvm/lib/MC/MCSectionCOFF.cpp
@@ -78,3 +78,7 @@
 bool MCSectionCOFF::UseCodeAlign() const {
   return getKind().isText();
 }
+
+bool MCSectionCOFF::isVirtualSection() const {
+  return getCharacteristics() & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
+}