perl-cross-debian updates

Working with perl upstream, we're getting closer to a fully cross-built upstream perl without needing the external perl installation. The branch (which is also available here with a few of my changes) now builds a host miniperl, cross-builds the rest of perl and almost gets through the rest of the build by using the host miniperl to handle the extensions up as far as XS::Typemap:

make[1]: Leaving directory `/home/neil/code/debian/src/perl/cross/git/perl/ext/XS-APItest'

./miniperl -Ilib make_ext.pl lib/auto/XS/Typemap/Typemap.so MAKE=make LIBPERL_A=libperl.a LINKTYPE=dynamic

	Making XS::Typemap (all)

make[1]: Entering directory `/home/neil/code/debian/src/perl/cross/git/perl/ext/XS-Typemap'

make[1]: Leaving directory `/home/neil/code/debian/src/perl/cross/git/perl/ext/XS-Typemap'

Making all in ext/XS-Typemap

make all PERL_CORE=1 LIBPERL_A=libperl.a LINKTYPE=dynamic

make[1]: Entering directory `/home/neil/code/debian/src/perl/cross/git/perl/ext/XS-Typemap'

make[1]: Leaving directory `/home/neil/code/debian/src/perl/cross/git/perl/ext/XS-Typemap'

./perl -f -Ilib pod/buildtoc -q

Can't load module Digest::MD5, dynamic loading not available in this perl.

  (You may need to build a new perl executable which either supports

  dynamic loading or has the Digest::MD5 module statically linked into it.)

 at Porting/pod_lib.pl line 4.

Compilation failed in require at Porting/pod_lib.pl line 4.

BEGIN failed--compilation aborted at Porting/pod_lib.pl line 4.

Compilation failed in require at pod/buildtoc line 17.

BEGIN failed--compilation aborted at pod/buildtoc line 18.

make: *** [pod/perltoc.pod] Error 2

Note the change from ./miniperl (which is itself a bug as it should be ./host/miniperl) to ./perl which is, naturally, an armel binary. It's also copied into the local directory, replacing the system perl if I copy it in.

So, more to do, but at least it gets this far.

Improved support for the extensions should also make it easier to clean up the current Debian cross-build diff which is the remaining bit of awkwardness / kludge.