libs/speex: version bump and refactoring

libs/speex: version bump and refactoring

- speexdsp has been broken out of the speex package by upstream. The
  released versions of both aren't aligned (speex is at 1.2.0, speexdsp
  at 1.2rc3). Break out speexdsp into its own Makefile accordingly.

- Don't disable VBR anymore as it has its applications (i.e. can be used
  with freeswitch-stable).

- Prevent build system from changing our CFLAGS (--enable-sse=no).

- Make integer mode depend on SOFT_FLOAT symbol so it doesn't get
  enabled on devices with FPUs.

- Use PKG_INSTALL and remove custom Build/Compile as there is no need
  for this.

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