Makefile: install 'git' in execdir

When a git command executes a subcommand, it uses the "git foo" form, which relies on finding "git" in the PATH. Normally this should not be a problem, since the same "git" that was used to invoke git in the first place will be found. And if somebody invokes a "git" outside of the PATH (e.g., by giving its absolute path), this case is already covered: we put that absolute path onto the front of PATH. However, if one is using "sudo", then sudo will execute the "git" from the PATH, but pass along a restricted PATH that may not contain the original "git" directory. In this case, executing a subcommand will fail. To solve this, we put the "git" wrapper itself into the execdir; this directory is prepended to the PATH when git starts, so the wrapper will always be found. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>