cext: extract revlog/index parsing code to own C file
parsers.c is ~3000 lines and ~2/3 of it is related to the revlog
index type.
We already have separate C source files for directory utilities
and manifest parsing. I think the quite unwieldy revlog/index
parsing code should be self-contained as well.
I performed the extraction as a file copy then removed content
from both sides in order to preserve file history and blame.
As part of this, I also had to move the hexdigit table and
function to a shared header since it is used by both parsers.c
and revlog.c
# no-check-commit
Test issue2761
$ hg init
$ touch to-be-deleted
$ hg add
adding to-be-deleted
$ hg ci -m first
$ echo a > to-be-deleted
$ hg ci -m second
$ rm to-be-deleted
$ hg diff -r 0
Same issue, different code path
$ hg up -C
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ touch does-not-exist-in-1
$ hg add
adding does-not-exist-in-1
$ hg ci -m third
$ rm does-not-exist-in-1
$ hg diff -r 1