[cfi-verify] Add blacklist parsing for result filtering.

Adds blacklist parsing behaviour for filtering results into four categories:

 - Expected Protected: Things that are not in the blacklist and are protected.
 - Unexpected Protected: Things that are in the blacklist and are protected.
 - Expected Unprotected: Things that are in the blacklist and are unprotected.
 - Unexpected Unprotected: Things that are not in the blacklist and are unprotected.

 now can optionally be invoked with a second command line argument, which specifies the blacklist file that the binary was built with.

Current  statistics for chromium:

Reviewers: vlad.tsyrklevich

Subscribers: mgorny, llvm-commits, pcc, kcc

Differential Revision: https://reviews.llvm.org/D39525

llvm-svn: 317364