strbuf: make sure buffer is zero-terminated
strbuf: make sure buffer is zero-terminated

strbuf_init does not zero-terminate the initial buffer when hint is
non-zero. Fix this so we can rely on the string to be zero-terminated
even if we haven't filled it with anything yet.

Signed-off-by: Erik Faye-Lund <2a8ffc07e8f57d80a2934ccc3dd1949354d82b2d@gmail.com>
Acked-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