Add support for building Clang UPC with configure/Makefile structure.
Fixes #31.

runtime/Makefile
	Enable building of UPC library.
runtime/libupc/Makefile
	New. Main makefile for building libupc.
runtime/libupc/Makefile.optional.in
	New. Makefile build options that are included at the top of the
        Makefile.
runtime/libupc/Makefile.rules.in
	New. Makefile rules an options.
runtime/libupc/config.h.in
	New. Libupc configure defines.
runtime/libupc/configure
	New. Regenerate from autoconf/configure.ac.
tools/driver/Makefile
	Add aliases for clang-upc and upc.
runtime/libupc/autoconf/configure.ac
runtime/libupc/autoconf/AutoRegen.sh
runtime/libupc/autoconf/ExportMap.map
runtime/libupc/autoconf/LICENSE.TXT
runtime/libupc/autoconf/aclocal.m4
runtime/libupc/autoconf/config.guess
runtime/libupc/autoconf/config.sub
runtime/libupc/autoconf/install-sh
runtime/libupc/autoconf/ltmain.sh
runtime/libupc/autoconf/m4/build_exeext.m4
runtime/libupc/autoconf/m4/c_printf_a.m4
runtime/libupc/autoconf/m4/check_gnu_make.m4
runtime/libupc/autoconf/m4/config_makefile.m4
runtime/libupc/autoconf/m4/config_project.m4
runtime/libupc/autoconf/m4/cxx_flag_check.m4
runtime/libupc/autoconf/m4/find_std_program.m4
runtime/libupc/autoconf/m4/func_isinf.m4
runtime/libupc/autoconf/m4/func_isnan.m4
runtime/libupc/autoconf/m4/func_mmap_file.m4
runtime/libupc/autoconf/m4/header_mmap_anonymous.m4
runtime/libupc/autoconf/m4/huge_val.m4
runtime/libupc/autoconf/m4/libtool.m4
runtime/libupc/autoconf/m4/link_options.m4
runtime/libupc/autoconf/m4/linux_mixed_64_32.m4
runtime/libupc/autoconf/m4/ltdl.m4
runtime/libupc/autoconf/m4/need_dev_zero_for_mmap.m4
runtime/libupc/autoconf/m4/path_tclsh.m4
runtime/libupc/autoconf/m4/rand48.m4
runtime/libupc/autoconf/m4/sanity_check.m4
runtime/libupc/autoconf/m4/single_cxx_check.m4
runtime/libupc/autoconf/m4/visibility_inlines_hidden.m4
runtime/libupc/autoconf/mkinstalldirs
        All the files under libupc/autoconf are copied from
        llvm/projects/simple.  All of them are identical to their source
        except for configure.ac which was modified for libupc configuration.