perf: define formatter locally for Mercurial earlier than 2.2
Before this patch, using ui.formatter() prevents perf.py from
measuring performance with Mercurial earlier than 2.2 (or
ae5f92e154d3), because ui.formatter() isn't available in such
Mercurial, even though there are some code paths for Mercurial earlier
than 2.2 in perf.py.
For example, setting "_prereadsize" attribute in perfindex() and
perfnodelookup() is effective only with hg earlier than 1.8 (or
61c9bc3da402).
This patch defines formatter class locally, and use it instead of the
value returned by ui.formatter(), if perf.py is used with Mercurial
earlier than 2.2.
In this case, we don't need to think about -T/--template option for
formatter, because previous patch made -T/--template disabled for
perf.py with Mercurial earlier than 3.2 (or
7a7eed5176a4).
https://bz.mercurial-scm.org/1877
$ hg init a
$ cd a
$ echo a > a
$ hg add a
$ hg ci -m 'a'
$ echo b > a
$ hg ci -m'b'
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg book main
$ hg book
* main 0:cb9a9f314b8b
$ echo c > c
$ hg add c
$ hg ci -m'c'
created new head
$ hg book
* main 2:d36c0562f908
$ hg heads
changeset: 2:d36c0562f908
bookmark: main
tag: tip
parent: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: c
changeset: 1:1e6c11564562
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
$ hg up 1e6c11564562
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(leaving bookmark main)
$ hg merge main
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg book
main 2:d36c0562f908
$ hg ci -m'merge'
$ hg book
main 2:d36c0562f908
$ cd ..