Fix crash for incomplete labels in macros.

Still the formatting can be improved, but at least we don't assert any
more. This happened when trying to format lib/Sema/SemaType.cpp.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175003 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Format/UnwrappedLineParser.cpp b/lib/Format/UnwrappedLineParser.cpp
index 9226716..28522a3 100644
--- a/lib/Format/UnwrappedLineParser.cpp
+++ b/lib/Format/UnwrappedLineParser.cpp
@@ -565,8 +565,8 @@
 }
 
 void UnwrappedLineParser::parseLabel() {
-  // FIXME: remove all asserts.
-  assert(FormatTok.Tok.is(tok::colon) && "':' expected");
+  if (FormatTok.Tok.isNot(tok::colon))
+    return;
   nextToken();
   unsigned OldLineLevel = Line->Level;
   if (Line->Level > 0)