freeswitch-stable: Fixes for modules and libs

freeswitch-stable: Fixes for modules and libs

- Add missed dependency on libyuv to libvpx.
- Get rid of gratuitous @ in Config.in.
- Clean up Perl and Python deps.
- Fix installation paths for the ESL packages.
- Don't set ac_cv_lib_perl_perl_alloc=yes, it's not needed.
- Get rid of the build dep on erlang. Have the modules (erlang_event and
  kazoo) depend on erlang instead; they both require epmd at runtime.
- Force spandsp and pocketsphinx to use fixed point math when soft float
  support is enabled for the target device.
- Make libvpx use OpenWrt/LEDE flags, otherwhise it comes up with
  optimized flags on its own.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>