Use a vector of pairs to implement the section stack, not two
independent vectors.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126099 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 3dcdba1..4b302c8 100644
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -20,8 +20,8 @@
 using namespace llvm;
 
 MCStreamer::MCStreamer(MCContext &Ctx) : Context(Ctx) {
-  PrevSectionStack.push_back(NULL);
-  CurSectionStack.push_back(NULL);
+  const MCSection *section = NULL;
+  SectionStack.push_back(std::make_pair(section, section));
 }
 
 MCStreamer::~MCStreamer() {