Makefile: building git in cygwin 1.7.0
Makefile: building git in cygwin 1.7.0

On platforms with $X, make removes any leftover scripts 'a' from
earlier builds if a new binary 'a.exe' is now built.  However, on
cygwin 1.7.0, 'git' and 'git.exe' now consistently name the same file.
Test for file equality before attempting a remove, in order to avoid
nuking just-built binaries.

Signed-off-by: Eric Blake <d9321fbaaa1b2c44636b6b3e2377f13b1584bbd6@byu.net>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git