MC: Add dyn_cast support to MCSection.
 - Of questionable utility, since in general anything which wants to do this should probably be within a target specific hook, which can rely on the sections being of the appropriate type. However, it can be useful for short term hacks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103980 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCSectionMachO.cpp b/lib/MC/MCSectionMachO.cpp
index 7a519e8..4ad3a2f 100644
--- a/lib/MC/MCSectionMachO.cpp
+++ b/lib/MC/MCSectionMachO.cpp
@@ -73,7 +73,7 @@
 
 MCSectionMachO::MCSectionMachO(StringRef Segment, StringRef Section,
                                unsigned TAA, unsigned reserved2, SectionKind K)
-  : MCSection(K), TypeAndAttributes(TAA), Reserved2(reserved2) {
+  : MCSection(SV_MachO, K), TypeAndAttributes(TAA), Reserved2(reserved2) {
   assert(Segment.size() <= 16 && Section.size() <= 16 &&
          "Segment or section string too long");
   for (unsigned i = 0; i != 16; ++i) {