libxml-parser-perl: Add a dependency on expat-native and pass in the

libxml-parser-perl: Add a dependency on expat-native and pass in the
appropriate libarary and include directories for exapt to the
makefile.
NOTE: This still doesn't work since it tries to use the host headers
when linking to perl. Fixing this properly will need "perl" to be
installed in the staging area (currently we stage perl-native only).