rust-index: add Sync bound to all relevant mmap-derived values
All readonly mmaps are Sync as far as Rust is concerned. Integrity of the
mmap'ed file is a concern separate to Rust's memory model, since it requires
out-of-program handling via locks, etc.
This will help when we start sharing the Rust Index with Python.
$ hg init repo
$ cd repo
$ echo a > a
$ hg ci -Ama
adding a
$ hg an a
0: a
$ hg --config ui.strict=False an a
0: a
$ echo "[ui]" >> $HGRCPATH
$ echo "strict=True" >> $HGRCPATH
$ hg an a
hg: unknown command 'an'
(use 'hg help' for a list of commands)
[10]
$ hg annotate a
0: a
should succeed - up is an alias, not an abbreviation
$ hg up
0 files updated, 0 files merged, 0 files removed, 0 files unresolved