strbuf: add strbuf_add_real_path()
Add a function for appending the canonized absolute pathname of a given
path to a strbuf. It keeps the existing contents intact, as expected of
a function of the strbuf_add() family, while avoiding copying the result
if the given strbuf is empty. It's more consistent with the rest of the
strbuf API than strbuf_realpath(), which it's wrapping.
Also add a semantic patch demonstrating its intended usage and apply it
to the current tree. Using strbuf_add_real_path() instead of calling
strbuf_addstr() and real_path() avoids an extra copy to a static buffer.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>