Import of code from heimdal

Import of code from heimdal

This commit updates the code imported from the external
heimdal git repository to their revision
48ad3e1e6597f03cce5439831ef94b5ec11894e9
which is described as switch-from-svn-to-git-1593-g48ad3e1

Change-Id: I90eb6752000d6794e830a704adcf367928b05a98
Reviewed-on: http://gerrit.openafs.org/2898
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>