revlog: rename 'self.checkinlinesize' into '_enforceinlinesize'
The name change has two motivations:
1) The function has no external caller, so we move it to protected space.
2) the function does more than checking it also split the data if we have more
data than 'inline' supports.
https://bz.mercurial-scm.org/1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..