filemerge: remove `uselocalpath` argument from `_maketempfiles()`
The `localpath` argument is unused if `uselocalpath` is false, so we
can use `None` as a sentinel value for the variable instead and remove
extra `uselocalpath` argument. That's not much of a win, but it's a
small step towards further improvements.
Differential Revision: https://phab.mercurial-scm.org/D12189
#require execbit
$ hg init repo
$ cd repo
$ echo foo > foo
$ chmod 644 foo
$ hg ci -qAm '644'
$ chmod 755 foo
$ hg ci -qAm '755'
reverting to rev 0
$ hg revert -a -r 0
reverting foo
$ hg st
M foo
$ hg diff --git
diff --git a/foo b/foo
old mode 100755
new mode 100644
$ cd ..