Merge branch 'rs/cocci'

Code cleanup.

* rs/cocci:
use strbuf_addstr() for adding constant strings to a strbuf, part 2
add coccicheck make target
contrib/coccinelle: fix semantic patch for oid_to_hex_r()

diff --cc Makefile
Simple merge

diff --cc builtin/submodule--helper.c
Simple merge

diff --cc merge-recursive.c
Simple merge

diff --cc wt-status.c
Simple merge