Add emscripten support to config.sub

build_tools/config.sub

 #! /bin/sh
 # Configuration validation subroutine script.
 #   Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
 #   2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
 #   2011, 2012 Free Software Foundation, Inc.
 
 timestamp='2012-02-10'
 
 # This file is (in principle) common to ALL GNU software.
 # The presence of a machine in this file suggests that SOME GNU software
@@ skipping 815 matching lines @@
                 os=-msys
                 ;;
         mvs)
                 basic_machine=i370-ibm
                 os=-mvs
                 ;;
         nacl)
                 basic_machine=le32-unknown
                 os=-nacl
                 ;;
+        emscripten)
+                basic_machine=asmjs-unknown
+                os=-emscripten
+                ;;
         ncr3000)
                 basic_machine=i486-ncr
                 os=-sysv4
                 ;;
         netbsd386)
                 basic_machine=i386-unknown
                 os=-netbsd
                 ;;
         netwinder)
                 basic_machine=armv4l-rebel
@@ skipping 644 matching lines @@
                 os=-kaos
                 ;;
         -zvmoe)
                 os=-zvmoe
                 ;;
         -dicos*)
                 os=-dicos
                 ;;
         -nacl*)
                 ;;
+        -emscripten*)
+                ;;
         -none)
                 ;;
         *)
                 # Get rid of the `-' at the beginning of $os.
                 os=`echo $os | sed 's/[^-]*-//'`
                 echo Invalid configuration \`$1\': system \`$os\' not recognized 1>&2
                 exit 1
                 ;;
 esac
 else
@@ skipping 254 matching lines @@
 
 echo $basic_machine$os
 exit
 
 # Local variables:
 # eval: (add-hook 'write-file-hooks 'time-stamp)
 # time-stamp-start: "timestamp='"
 # time-stamp-format: "%:y-%02m-%02d"
 # time-stamp-end: "'"
 # End: