match: optimize matcher when all patterns are of rootfilesin kind Internally at Google, we use narrowspecs with only rootfilesin-kind patterns. Sometimes there are thousands of such patterns (i.e. thousands of tracked directories). In such cases, it can take quite long to build and evaluate the resulting matcher. This patch optimizes matchers that have only patterns of rootfilesin so it instead of creating a regular expression, it matches the given file's directory against the set of directories. In a repo with ~3600 tracked directories, it takes about 1.35 s to build the matcher and 2.7 s to walk the dirstate before this patch. After, it takes 0.04 s to create the matcher and 0.87 s to walk the dirstate. It may be worthwhile to do similar optimizations for e.g. patterns of type "kind:", but that's not a priority for us right now. Differential Revision: https://phab.mercurial-scm.org/D5058