Depends.pm: use $DLEXT instead of $SO for library filename extensions

- Patch file 'ExtUtils-Depends-part1-dlext.diff' from kmx in RT#92699
MANIFEST: remove MYMETA.* files

- EU::MM throws a warning when 'perl Makefile.PL' is run and the
  MYMETA.* files listed in the MANIFEST don't exist in the distro; the
  MYMETA.* files are generated automatically by EU::MM during 'perl
  Makefile.PL', so no need to have them in the MANIFEST
use DynaLoader::mod2fname if available

mod2fname isn't exactly well documented, but basically, some
platforms have some unusual requirements for their library
names, so instead of, say, Utils.so for List::Utils, you
might end up with PL_List__Utils.so; what mod2fname does is
get you that library name.

There's currently two systems with mod2fname defined, VMS
and Android. OS/2 uses it as well, but the OS/2 port isn't
functional at the moment. Additionally, Windows may start
using it in the near future.
Added Android support
Added empty files for testing d_libname_unique
t/04_extra_libs.t: added 'android' to skipped tests message
Stable Release 0.309