Create a virscsihost.c and place the functions there. That removes the
last #ifdef __linux__ from virutil.c.
Take the opporunity to also change the function names and in one case
the parameters slightly
This updates the test program to make it consistent with recent changes
to the mock libraries, and also opens up the possibility of mocking more
than just /sys in the future.
Introduce a new function to parse the provided scsi_host parent address
and unique_id value in order to find the /sys/class/scsi_host directory
which will allow a stable SCSI host address
Add a test to scsihosttest to lookup the host# name by using the PCI address
and unique_id value
Introduce a new function to read the current scsi_host entry and return
the value found in the 'unique_id' file.
Add a 'scsihosttest' test (similar to the fchosttest, but incorporating some
of the concepts of the mocked pci test library) in order to read the
unique_id file like would be found in the /sys/class/scsi_host tree.
