Merge branch 'cw/maint-exec-defpath'

* cw/maint-exec-defpath:
autoconf: Check if <paths.h> exists and set HAVE_PATHS_H
exec_cmd.c: replace hard-coded path list with one from <paths.h>

diff --cc Makefile
Simple merge

diff --cc configure.ac
Simple merge

diff --cc exec_cmd.c
Simple merge

diff --cc git-compat-util.h
Simple merge