[UpdateCCTestChecks] Detect function mangled name on separate line

Sometimes functions with large comment blocks in front of them have their
declarations output on several lines by c-index-test.  Hence the one-line
function name/line/mangled pattern will not work to detect them.  Break the
pattern up into two patterns and keep state after seeing the name/line
information until we finally see the mangled name.

Differential Revision: https://reviews.llvm.org/D68272

llvm-svn: 374078