added a skeleton of the ARM backend


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28301 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 3917db0..b29ce31 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -285,7 +285,7 @@
     [Build specific host targets: all,host-only,{target-name} (default=all)]),,
     enableval=all)
 case "$enableval" in
-  all) TARGETS_TO_BUILD="X86 Sparc PowerPC Alpha IA64" ;;
+  all) TARGETS_TO_BUILD="X86 Sparc PowerPC Alpha IA64 ARM" ;;
   host-only)
     case "$llvm_cv_target_arch" in
       x86)     TARGETS_TO_BUILD="X86" ;;