CrashRecovery: Use ThreadLocal::erase() instead of set(0).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109752 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/CrashRecoveryContext.cpp b/lib/Support/CrashRecoveryContext.cpp
index 1213484..4514a99 100644
--- a/lib/Support/CrashRecoveryContext.cpp
+++ b/lib/Support/CrashRecoveryContext.cpp
@@ -31,7 +31,7 @@
     CurrentContext.set(this);
   }
   ~CrashRecoveryContextImpl() {
-    CurrentContext.set(0);
+    CurrentContext.erase();
   }
 
   void HandleCrash() {