ART: Refactored regex code in Checker

This patch refactors how Checker constructs regular expressions which
it uses to parse tests and verify compiler output. It also replaces
all occurrences of the '[0-9]+' ID-matching expression with the '\d+'
shorthand.

Change-Id: I5f854a25707e44ed2fa1673ff084990e8f43e4a2
3 files changed