[PATCH] Makefile: rebuild git.o on version change, clean up git$X flags

Commit 334d28ae factored out git.o as an intermediate stage between git.c and git$X. However:

- It left some no-longer-relevant flags in the rule for git$X.

- It failed to replace git$X with git.o in the list of files that
  record GIT_VERSION.  This broke incorporation of a changed
  GIT_VERSION into git$X because, when GIT_VERSION changes, git.o isn't
  remade and git$X is relinked from the git.o that still contains the
  old GIT_VERSION.

This patch removes the irrelevant flags and fixes incorporation of a changed GIT_VERSION into git$X.

Signed-off-by: Matt McCutchen <hashproduct@gmail.com>
---
Amusingly, I found this because, when I formatted my previous patch for
submission, I noticed that the "-dirty" in the version at the bottom
wouldn't go away even though I had committed my changes to my
git-development repository.  (I was actually using the git tools from
that repository.)

 Makefile |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)