clang-format: Prevent weird line-wraps in complex lambda introducers

Before:
  aaaaaaaaa.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
      [aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa]() -> ::std::
	  unordered_set<aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa> {
	    //
	  });

After:
  aaaaaaaaa.aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
      [aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa]()
	  -> ::std::unordered_set<
	      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa> {
	//
      });

llvm-svn: 295659