[clang-format] disable adding extra space after MSVC '__super' keyword

clang-format treats MSVC `__super` keyword like all other keywords adding
a single space after. This change disables this behavior for `__super`.

Patch originally by jutocz (thanks!).

Differential Revision: https://reviews.llvm.org/D30932

llvm-svn: 297936
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 674c3b5..6a250eb 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -9977,6 +9977,10 @@
             format("auto a = unique_ptr < Foo < Bar>[10]> ;", Spaces));
 }
 
+TEST_F(FormatTest, NoSpaceAfterSuper) {
+    verifyFormat("__super::FooBar();");
+}
+
 TEST(FormatStyle, GetStyleOfFile) {
   vfs::InMemoryFileSystem FS;
   // Test 1: format file in the same directory.