let configure recognize Alphas


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19810 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/configure b/configure
index d0bb974..bc9d4d9 100755
--- a/configure
+++ b/configure
@@ -1790,6 +1790,7 @@
   amd64-* | x86_64-*)     llvm_cv_target_arch="x86_64" ;;
   sparc*-*)               llvm_cv_target_arch="Sparc" ;;
   powerpc*-*)             llvm_cv_target_arch="PowerPC" ;;
+  alpha*-*)               llvm_cv_target_arch="Alpha" ;;
   *)                      llvm_cv_target_arch="Unknown" ;;
 esac
 fi