treemanifest: stop storing full path for each item in manifest._lazydirs
This information is obtainable, if needed, based on the lazydirs key (which is
the entry name) and the manifest's `dir()` method.
### Performance
This is actually both a memory and a performance improvement, but it's likely to
be a very small one in most situations. In the pathological repo I've been using
for testing other performance work I've done recently, this reduced the time for
a rebase operation (rebasing two commits across a public-phase change that
touches a sibling of one of my tracked directories where the common parent is
massive (>>10k entries)):
#### Before
```
Time (mean ± σ): 4.059 s ± 0.121 s [User: 0.9 ms, System: 0.6 ms]
Range (min … max): 3.941 s … 4.352 s 10 runs
```
#### After
```
Time (mean ± σ): 3.707 s ± 0.060 s [User: 0.8 ms, System: 0.8 ms]
Range (min … max): 3.648 s … 3.818 s 10 runs
```
Differential Revision: https://phab.mercurial-scm.org/D9553
#require test-repo slow debhelper debdeps
$ . "$TESTDIR/helpers-testrepo.sh"
$ testrepohgenv
Ensure debuild doesn't run the testsuite, as that could get silly.
$ DEB_BUILD_OPTIONS=nocheck
$ export DEB_BUILD_OPTIONS
$ OUTPUTDIR=`pwd`
$ export OUTPUTDIR
$ cd "$TESTDIR"/..
$ make deb > $OUTPUTDIR/build.log 2>&1
$ cd $OUTPUTDIR
$ ls *.deb | grep -v 'dbg'
mercurial_*.deb (glob)
should have .so and .py
$ dpkg --contents mercurial_*.deb | egrep '(localrepo|parsers)'
* ./usr/lib/python3/dist-packages/mercurial/cext/parsers*.so (glob)
* ./usr/lib/python3/dist-packages/mercurial/localrepo.py (glob)
* ./usr/lib/python3/dist-packages/mercurial/pure/parsers.py (glob)
should have zsh completions
$ dpkg --contents mercurial_*.deb | egrep 'zsh.*[^/]$'
* ./usr/share/zsh/vendor-completions/_hg (glob)
should have chg
$ dpkg --contents mercurial_*.deb | egrep 'chg$'
* ./usr/bin/chg (glob)
chg should come with a man page
$ dpkg --contents mercurial_*.deb | egrep 'man.*chg'
* ./usr/share/man/man1/chg.1.gz (glob)