pyaudio: fix build on darwin

* `portaudio`: remove `alsaLib` from build inputs, add '--build=x86_64'
  '--without-oss' '--with-host-os=darwin' to configureFlags, add
  framework header files, copy darwin-specific header on install,
  build with `gccApple` (resolves a variety of syntax errors in the source),
  patch Makefile and libtool to remove specific references to 10.4 SDK
* `pyaudio`: build with '--static-link' flag, set correct PORTAUDIO_PATH
  environment variable