patch applied (packages/unix): Move System.Posix.Signals from base

[Ian Lynagh]

Sun Jul 29 14:56:17 PDT 2007  Ian Lynagh <igloo at earth.li>
  * Move System.Posix.Signals from base
  Also adds System.Posix.Process.Internals in order to make the deps work out.

    A ./System/Posix/Process/
    M ./System/Posix/Process.hsc -1 +1
    A ./System/Posix/Process/Internals.hs
    A ./System/Posix/Signals.hs
    A ./cbits/execvpe.c
    A ./include/execvpe.h
    M ./unix.cabal -5 +7