Add support for subsections to the ELF assembler. Fixes PR8717.

Differential Revision: http://llvm-reviews.chandlerc.com/D598

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179725 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCParser/DarwinAsmParser.cpp b/lib/MC/MCParser/DarwinAsmParser.cpp
index 6d6409f..7eb8b74 100644
--- a/lib/MC/MCParser/DarwinAsmParser.cpp
+++ b/lib/MC/MCParser/DarwinAsmParser.cpp
@@ -566,10 +566,10 @@
 /// ParseDirectivePrevious:
 ///   ::= .previous
 bool DarwinAsmParser::ParseDirectivePrevious(StringRef DirName, SMLoc) {
-  const MCSection *PreviousSection = getStreamer().getPreviousSection();
-  if (PreviousSection == NULL)
+  MCSectionSubPair PreviousSection = getStreamer().getPreviousSection();
+  if (PreviousSection.first == NULL)
       return TokError(".previous without corresponding .section");
-  getStreamer().SwitchSection(PreviousSection);
+  getStreamer().SwitchSection(PreviousSection.first, PreviousSection.second);
   return false;
 }