Add support for pushsection and popsection. Patch by Joerg Sonnenberger.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125629 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCPureStreamer.cpp b/lib/MC/MCPureStreamer.cpp
index 5341844..6098e6b 100644
--- a/lib/MC/MCPureStreamer.cpp
+++ b/lib/MC/MCPureStreamer.cpp
@@ -113,9 +113,9 @@
 void MCPureStreamer::EmitLabel(MCSymbol *Symbol) {
   assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
   assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
-  assert(CurSection && "Cannot emit before setting section!");
+  assert(getCurrentSection() && "Cannot emit before setting section!");
 
-  Symbol->setSection(*CurSection);
+  Symbol->setSection(*getCurrentSection());
 
   MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);