clang-format: Fix corner case in ObjC interface definitions.

In
  @implementation ObjcClass
  - (void)method;
  {
  }
  @end
the ObjC compiler seems to accept the superfluous comma after "method",
but clang-format used to assert on the subsequent "{".

This fixes llvm.org/PR16604.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189453 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/Format/FormatTest.cpp b/unittests/Format/FormatTest.cpp
index 274d6e0..24ba93f 100644
--- a/unittests/Format/FormatTest.cpp
+++ b/unittests/Format/FormatTest.cpp
@@ -4791,6 +4791,10 @@
   verifyFormat("@implementation Foo (HackStuff)\n"
                "+ (id)init {\n}\n"
                "@end");
+  verifyFormat("@implementation ObjcClass\n"
+               "- (void)method;\n"
+               "{}\n"
+               "@end");
 }
 
 TEST_F(FormatTest, FormatObjCProtocol) {