MFC r303830,r304693,r304694,r304698:

r303830:

Remove vestigal references to alpha

Replace alpha reference in getconf(1) with amd64 [*]

PR: 211300 [*]

r304693:

Clean up trailing whitespace

r304694:

Add MIN_HOLE_SIZE pathconf(2) support to getconf

This allows shell programs to programmatically determine whether
or not a filesystem supports sparse files

r304698:

Add support for _PC_ACL_NFS4 as TRUSTEDBSD_ACL_NFS4

The TRUSTEDBSD prefix was chosen for consistency with the other
related _PC_ACL* prefixed variables.