generator: Export libxml2 CLEANUP_* macros unconditionally.

These call abort() if libxml2 is not actually installed, but that
should never happen inside the library or tools.
tools: Use CLEANUP_* macros in several C tools.
rescue: Count the mountable filesystems when displaying the 'suggest' message.
Version 1.21.9.
launch: libvirt: Make it clear that setsockcreatecon debug message is just a warning.

This was disturbing to some users, but other users saw the warning
when it was really something they should pay attention to.  Make it
clear that it's a warning, unless people are really using SELinux +
sVirt.

Thanks: Richard Harman.