Improve detection preventing certain kind of formatting patterns.

An oversight in this detection made clang-format unable to format
the following nicely:
void aaaaaaaaaaaaaaaaaaa<aaaaaaaaaaaaaaaaaaaaaaaaaaa,
                         bbbbbbbbbbbbbbbbbbbbbbbbbb>(
    cccccccccccccccccccccccccccc);

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@183097 91177308-0d34-0410-b5e6-96231b3b80d8