Abstract SSH setup to support GIT_SSH

In order to honor GIT_SSH the TransportGitSsh class needs to run the
process named by the GIT_SSH environment variable and use that as the
pipes for connectivity to the remote peer.  Refactor the current
transport code to support a different type of pipe connectivity, so we
can later add GIT_SSH.

Bug: 321062
Change-Id: I9d8ee1a95f1bac5013b33a4a42dcf1f98f92172f
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
1 file changed