Overall UNIX build system improvements:
Overall UNIX build system improvements:

* Makefile header is now completely dynamic
* Absolute paths in (top_)?(src|build)dir and VPATH
  (fixes Tru64 support)
* VPATH does not contain variables anymore
  (fixes UnixWare support)


marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core