This adds standard LICENSE and BUGS sections to all of the man pages
that are processed by podwrapper.
Modify all the calls to $(PODWRAPPER) to add the right --license
parameter according to the content. Note that this relaxes the
license on some code example pages, making them effectively BSD-style
licensed.
This uses Pod::Simple so it properly parses the input POD and can
generate proper custom output as required specifically by libguestfs.
One immediate benefit is that links between and within manual pages
now work mostly correctly.