rootcheck: don't traverse NFS/CIFS mounts

Conflicts:
	src/rootcheck/check_rc_sys.c
Added <skip_nfs>yes</skip_nfs> option to rootcheck to control whether
NFS mounts are scanned.  The defaults do scan NFS mounts, which is
consistent with existing functionality.
Fix definition check.
rootcheck: don't traverse NFS/CIFS mounts

Conflicts:
	src/rootcheck/check_rc_sys.c
Added <skip_nfs>yes</skip_nfs> option to rootcheck to control whether
NFS mounts are scanned.  The defaults do scan NFS mounts, which is
consistent with existing functionality.
Add NFS skipping to syscheck as well.
Merge branch 'feature/nfs_cifs_exclusion' of github.com:reyjrar/ossec-hids into feature/nfs_cifs_exclusion

Conflicts:
	src/headers/fs_op.h
	src/shared/fs_op.c
Remove unnecessary error message declaration.
Remove duplicate definition of os_shell_escape.
Fix rootcheck.conf to use the skip_nfs option