ApiLint: Performance improvements for 2.0 signature format parsing

Test: tools/apilint/apilint_sha.sh HEAD
Test: python tools/apilint/apilint_test.py
Change-Id: I76b979dd81702afce6468ac377230e589a25e08f
(cherry picked from commit a30d062775da3812589a6ce3e49be9d697ef0d6d)
1 file changed