Makefile: build default goal before running tests
Makefile: build default goal before running tests

We add the default Makefile goal, namely, the local "git-lfs" binary
in our "bin/" directory, as a dependency for the "make test" target.
This ensures the local binary has been created and is up-to-date
before the Go tests run.

Otherwise, when running "make test" in a fresh clone or where the
local binary does not yet exist for some other reason, the test suite
will invoke whatever other "git-lfs" binary exists on the system rather
than one local to the working tree, despite the adjustment of the
PATH environment variable added in commit 6f6b353c25b7.

github/git-lfs,github/git-lfs,github/git-lfs