Add initial support for *-*-nacl target.

autoconf/configure.ac

 dnl === configure.ac --------------------------------------------------------===
 dnl                     The LLVM Compiler Infrastructure
 dnl
 dnl This file is distributed under the University of Illinois Open Source
 dnl License. See LICENSE.TXT for details.
 dnl
 dnl===-----------------------------------------------------------------------===
 dnl This is the LLVM configuration script. It is processed by the autoconf
 dnl program to produce a script named configure. This script contains the
 dnl configuration checks that LLVM needs in order to support multiple platforms.
@@ skipping 281 matching lines @@
   *-*-auroraux*)
     llvm_cv_target_os_type="AuroraUX" ;;
   *-*-win32*)
     llvm_cv_target_os_type="Win32" ;;
   *-*-mingw*)
     llvm_cv_target_os_type="MingW" ;;
   *-*-haiku*)
     llvm_cv_target_os_type="Haiku" ;;
   *-*-rtems*)
     llvm_cv_target_os_type="RTEMS" ;;
+  *-*-nacl*)
+    llvm_cv_target_os_type="NativeClient" ;;
   *-unknown-eabi*)
     llvm_cv_target_os_type="Freestanding" ;;
   *)
     llvm_cv_target_os_type="Unknown" ;;
 esac])
 
 dnl Make sure we aren't attempting to configure for an unknown system
 if test "$llvm_cv_os_type" = "Unknown" ; then
   AC_MSG_ERROR([Operating system is unknown, configure can't continue])
 fi
@@ skipping 1458 matching lines @@
 AC_CONFIG_MAKEFILE(test/Makefile.tests)
 AC_CONFIG_MAKEFILE(unittests/Makefile)
 AC_CONFIG_MAKEFILE(tools/Makefile)
 AC_CONFIG_MAKEFILE(utils/Makefile)
 AC_CONFIG_MAKEFILE(projects/Makefile)
 AC_CONFIG_MAKEFILE(bindings/Makefile)
 AC_CONFIG_MAKEFILE(bindings/ocaml/Makefile.ocaml)
 
 dnl Finally, crank out the output
 AC_OUTPUT