Write PJSIP config_site.h as part of the compilation patching procedure

darcs-hash:20090415111843-58103-99f90047da292140f651af1326b4ef890989848a
Readded disabling L16 codec compilation, fix is in PJSIP SVN branch 1.0.x

darcs-hash:20090415111919-58103-c90073bb8dccbad71e4ddbc959c10d3196009e6f