[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