check-code: move fixing up regexp into main procedure This patch makes an extra check pattern to be prepared by "_preparepats()" as similarly as existing patterns, if it is added to "checks" array before invocation of "main()" in check-code.py. This is a part of preparation for adding check-code.py extra checks by another python script in subsequent patch. This is also useful for SkeletonExtensionPlan. https://www.mercurial-scm.org/wiki/SkeletonExtensionPlan