clang-format: Fix incorrect cast detection.

Before:
  auto s = sizeof...(Ts)-1;

After:
  auto s = sizeof...(Ts) - 1;

llvm-svn: 272536
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index d27da34..7e3b4ce 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -5494,6 +5494,7 @@
 
 TEST_F(FormatTest, UnderstandsBinaryOperators) {
   verifyFormat("COMPARE(a, ==, b);");
+  verifyFormat("auto s = sizeof...(Ts) - 1;");
 }
 
 TEST_F(FormatTest, UnderstandsPointersToMembers) {