store: optimize fncache._load a bit by dirdecoding the contents in one go
For a netbeans clone on Windows 7 x64:
Before:
$ hg perffncacheload
! wall 0.124000 comb 0.124801 user 0.124801 sys 0.000000 (best of 76)
After:
$ hg perffncacheload
! wall 0.096000 comb 0.093601 user 0.078001 sys 0.015600 (best of 97)
$ "$TESTDIR/hghave" inotify || exit 80
$ hg init
$ echo "[extensions]" > .hg/hgrc
$ echo "inotify=" >> .hg/hgrc
$ hg inserve -d --pid-file .hg/inotify.pid
$ echo a > a
$ hg ci -Aqm0
$ hg co -q null
$ hg co -q
$ hg st
$ cat a
a
$ kill `cat .hg/inotify.pid`