tests/test-manifest.t

inno: replace add_path.exe with a Pascal script

While attempting to build the Inno installer, I was unable to
find a copy of add_path.exe from the source site previously
listed in the docs.

Some quick Googling revealed that achieving this functionality
in native Pascal scripts seems to be preferred these days.

This commit vendors "Modify Path" (fetched from
https://www.legroom.net/software/modpath) and plugs it into
our Inno config file per its instructions.

The existing Inno installer appears to only modify PATH for
the current user (as opposed to at the system level). I've
maintained this behavior with Modify Path. Although it would
be trivial to change or add checkboxes to control the behavior.
I'll leave this as a follow-up.

Differential Revision: https://phab.mercurial-scm.org/D6060

Source bundle was generated with the following script:

# hg init
# echo a > a
# ln -s a l
# hg ci -Ama -d'0 0'
# mkdir b
# echo a > b/a
# chmod +x b/a
# hg ci -Amb -d'1 0'

  $ hg init
  $ hg unbundle "$TESTDIR/bundles/test-manifest.hg"
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 3 changes to 3 files
  new changesets b73562a03cfe:5bdc995175ba (2 drafts)
  (run 'hg update' to get a working copy)

The next call is expected to return nothing:

  $ hg manifest

  $ hg co
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg manifest
  a
  b/a
  l

  $ hg files -vr .
           2   a
           2 x b/a
           1 l l
  $ hg files -r . -X b
  a
  l
  $ hg files -T '{path} {size} {flags}\n'
  a 2 
  b/a 2 x
  l 1 l
  $ hg files -T '{path} {node|shortest}\n' -r.
  a 5bdc
  b/a 5bdc
  l 5bdc

  $ hg manifest -v
  644   a
  755 * b/a
  644 @ l
  $ hg manifest -T '{path} {rev}\n'
  a 1
  b/a 1
  l 1

  $ hg manifest --debug
  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a
  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 755 * b/a
  047b75c6d7a3ef6a2243bd0e99f94f6ea6683597 644 @ l

  $ hg manifest -r 0
  a
  l

  $ hg manifest -r 1
  a
  b/a
  l

  $ hg manifest -r tip
  a
  b/a
  l

  $ hg manifest tip
  a
  b/a
  l

  $ hg manifest --all
  a
  b/a
  l

The next two calls are expected to abort:

  $ hg manifest -r 2
  abort: unknown revision '2'!
  [255]

  $ hg manifest -r tip tip
  abort: please specify just one revision
  [255]