match: remove ctx argument from code path down to _buildmatch() 'ctx' was there only for filesets.

match: compose 'set:' pattern as matcher Baby step towards porting fileset to matcher composition. We can't use the exactmatcher since it would provide a computed set as exact paths. That's why we use the predicatematcher with fset.__contains__. This will be cleaned up later. The test change in test-glog.t means that the "set:copied()" pattern is no longer be processed as a slow path. That's because the fset is empty. This will also change in future patches.

match: resolve 'set:' patterns first in _buildmatch() This just makes the next patch less complicated. The order of 'set:' and 'subinclude:' expansion doesn't matter.