built-in add -p: implement the '/' ("search regex") command
This patch implements the hunk searching feature in the C version of
`git add -p`.
A test is added to verify that this behavior matches the one of the Perl
version of `git add -p`.
Note that this involves a change of behavior: the Perl version uses (of
course) the Perl flavor of regular expressions, while this patch uses
the regcomp()/regexec(), i.e. POSIX extended regular expressions. In
practice, this behavior change is unlikely to matter.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>