Enable Git to resolve its own binary location using a variety of
OS-specific and generic methods, including:

- procfs via "/proc/self/exe" (Linux)
- _NSGetExecutablePath (Darwin)
- KERN_PROC_PATHNAME sysctl on BSDs.
- argv0, if absolute (all, including Windows).

This is used to enable RUNTIME_PREFIX support for non-Windows systems,
notably Linux and Darwin. When configured with RUNTIME_PREFIX, Git will
do a best-effort resolution of its executable path and automatically use
this as its "exec_path" for relative helper and data lookups, unless
explicitly overridden.

Small incidental formatting cleanup of "exec_cmd.c".

Signed-off-by: Dan Jacques <dnj@google.com>
Thanks-to: Robbie Iannucci <iannucci@google.com>
Thanks-to: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Broaden the RUNTIME_PREFIX flag to configure Git's Perl scripts to
locate the Git installation's Perl support libraries by resolving
against the script's path, rather than hard-coding that path at
build-time. Hard-coding at build time worked on previous
RUNTIME_PREFIX configurations (i.e., Windows) because the Perl
scripts were run within a virtual filesystem whose paths were
consistent regardless of the location of the actual installation.
This will no longer be the case for non-Windows RUNTIME_PREFIX users.

When enabled, RUNTIME_PREFIX now requires Perl's system paths to be
expressed relative to a common installation directory in the Makefile,
and uses that relationship to locate support files based on the known
starting point of the script being executed, much like RUNTIME_PREFIX
does for the Git binary.

This change enables Git's Perl scripts to work when their Git installation
is relocated or moved to another system, even when they are not in a
virtual filesystem environment.

Signed-off-by: Dan Jacques <dnj@google.com>
Thanks-to: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Thanks-to: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Currently, the generated Perl script headers are emitted by commands in
the Makefile. This mechanism restricts options to introduce alternative
header content, needed by Perl runtime prefix support, and obscures the
origin of the Perl script header.

Change the Makefile to generate a header by processing a template file and
move the header content into the "perl/" subdirectory. The generated
header content will now be stored in the "GIT-PERL-HEADER" file. This
allows the content of the Perl header to be controlled by changing the path
of the template in the Makefile.

Signed-off-by: Dan Jacques <dnj@google.com>
Thanks-to: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Thanks-to: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Update funcname pattern used for C# to recognize "async" keyword.

* tl/userdiff-csharp-async:
  userdiff.c: add C# async keyword in diff pattern

Allow running a couple of tests with "sh -x".

* sg/cvs-tests-with-x:
  t9402-git-cvsserver-refs: don't check the stderr of a subshell
  t9400-git-cvsserver-server: don't rely on the output of 'test_cmp'

Doc update.

* ab/man-sec-list:
  git manpage: note git-security@googlegroups.com

Clean-up to various pieces of Perl code we have.

* ab/perl-fixes:
  perl Git::LoadCPAN: emit better errors under NO_PERL_CPAN_FALLBACKS
  Makefile: add NO_PERL_CPAN_FALLBACKS knob
  perl: move the perl/Git/FromCPAN tree to perl/FromCPAN
  perl: generalize the Git::LoadCPAN facility
  perl: move CPAN loader wrappers to another namespace
  perl: update our copy of Mail::Address
  perl: update our ancient copy of Error.pm
  git-send-email: unconditionally use Net::{SMTP,Domain}
  Git.pm: hard-depend on the File::{Temp,Spec} modules
  gitweb: hard-depend on the Digest::MD5 5.8 module
  Git.pm: add the "use warnings" pragma
  Git.pm: remove redundant "use strict" from sub-package
  perl: *.pm files should not have the executable bit

"git send-email" learned "--reply-to=<address>" option.

* cl/send-email-reply-to:
  send-email: support separate Reply-To address
  send-email: rename variable for clarity

Code refactoring.

* np/send-email-header-parsing:
  send-email: extract email-parsing code into a subroutine