Merge branch 'cc/access-on-aix-workaround'

Workaround for standard-compliant but less-than-useful behaviour of
access(2) for the root user.

* cc/access-on-aix-workaround:
git-compat-util: work around for access(X_OK) under root

diff --cc Makefile
Simple merge

diff --cc config.mak.uname
Simple merge

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