format_config: don't init strbuf
format_config: don't init strbuf

It's unusual for a function which writes to a passed-in
strbuf to call strbuf_init; that will throw away anything
already there, leaking memory. In this case, there are
exactly two callers; one relies on this initialization and
the other passes in an already-initialized buffer.

There's no leak, as the initialized buffer doesn't have
anything in it. But let's bump the strbuf_init out to the
one caller who needs it, making format_config more
idiomatic.

Signed-off-by: Jeff King <696e3fbcf235d40b6ea1ebd61c87cbea79d444e7@peff.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