Added configure/Makefile build for Clang UPC.  Supports SMP runtime.

- autoconf - directory borrowed from projects/sample directory.  It probbaly
  needs more cleanup and remove the unnecesary things.
- autoconf/configure.ac - main autoconf file. Adopted GUPC configure options
  for libupc.
- Makefile - main Makefile for building.  Provides rules for making linker
  script, clang-upc-lib.h, upc crt stuff files, UPC compiler rules, and all
source files.
- Makefile.optional.in - configure processed part of the makefile for enabling
  build options (backtrace, linker scirpt, etc).  Must be included before the
Clang makefile is included.
- Makefile.rules.in - various compiler options for building libupc.  Must be
  included after the Clang makefile is included.
- tools/driver/Makefile - add UPCTOOLSLALIAS for upc language aliases.