perl 5.8.8: Fixes for uclibc and libxml-parser-perl.

perl 5.8.8: Fixes for uclibc and libxml-parser-perl.
* Stage the headers from perl
* Modify cpan.bbclass to use the appropriate headers.
* Remove prototypes as well as disabling functions that uclibc doesn't
  support.
* Bump PR on libxml-parser-perl to force it to be rebuilt.
Previously it was always using the headers from native-perl, since the
headers were the same for native and target... but that's only true in the
case of glibc, for uclibc the headers are different.