Fixes a warning that reported that the SSH keys for existing accounts
did not exist while it did (resolve_path did not completely resolve).
perl 5.10 -> 5.8 in hope to work on msysgit, now that our fatpacked
build also bundles core perl modules (Pod::*) missing from msysgit.

Fixes to work with the perl bundled with msysgit. This perl 5.8.8 built
with the msys POSIX-like emulation.
The issues fixed:
- perl 5.8.8 compat (from 5.10 source): regexps (\K, *+), ~~, //
- msys issues: POSIX-like on Win32
  - path separator is '/' instead of '\' in file I/O (resolve_path)
  - ~/.ssh/config must be in CRLF (so the user can edit it with Notepad),
    so we have to explicitely enable the :crlf layer

Fixes to make release.pl work on Win32 to be able to rebuild
github-keygen to test it on msysgit's perl.
The Git part is not tested yet.

Pod::Simple is used by Pod::Usage so we have to pack it. This makes a
400 Kb build :(. Will have to check later how to reduce this.

Also avoid to fail if the 'fatlib' does not initally exists (just after
a fresh checkout).

Nearly works on Win32!
(IPC::Run or maybe Win32::Process, seems to have an issue when a command-line
contains two elements that are double quoted (the command itself and an
argument).

Thanks Maddingue for the tip!