audit: consolidate handling of mm->exe_file

This patch adds a audit_log_d_path_exe() helper function
to share how we handle auditing of the exe_file's path.
Used by both audit and auditsc. No functionality is changed.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
[PM: tweaked subject line]
Signed-off-by: Paul Moore <pmoore@redhat.com>

diff --cc kernel/audit.c
Simple merge

diff --cc kernel/audit.h
Simple merge

diff --cc kernel/auditsc.c
Simple merge