meson: port perl build scripts to python

It looks like it should be possible to port the handful of Perl scripts used as part of the Meson build to Python, which would be very useful for the GStreamer monorepo build on Windows where we would like to have a 'just works out of the box' experience.

Looks like it's mostly just some regexp replacements, which should be easy to port over.

~/Devel/libvpx/build/make$ wc -l *pl *pm
   39 ads2armasm_ms.pl
  114 ads2gas_apple.pl
  157 ads2gas.pl
  528 rtcd.pl
   60 thumb.pm
  898 total