Save/load POSIXThreads flag for PCH

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@80916 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/PCHReader.cpp b/lib/Frontend/PCHReader.cpp
index 55dbd97..4fcf026 100644
--- a/lib/Frontend/PCHReader.cpp
+++ b/lib/Frontend/PCHReader.cpp
@@ -1702,6 +1702,7 @@
     PARSE_LANGOPT(Freestanding);
     PARSE_LANGOPT(NoBuiltin);
     PARSE_LANGOPT(ThreadsafeStatics);
+    PARSE_LANGOPT(POSIXThreads);
     PARSE_LANGOPT(Blocks);
     PARSE_LANGOPT(EmitAllDecls);
     PARSE_LANGOPT(MathErrno);