clang-format: Correctly detect multiplication in ctor initializer.

Before:
  Constructor() : a(a), area(width *height) {}

After:
  Constructor() : a(a), area(width * height) {}

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@222010 91177308-0d34-0410-b5e6-96231b3b80d8