Add aarch64 to config.guess

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202125 91177308-0d34-0410-b5e6-96231b3b80d8

autoconf/config.guess

@@ -864,6 +864,9 @@ EOF
     i*86:Minix:*:*)
 	echo ${UNAME_MACHINE}-pc-minix
 	exit ;;
+    aarch64*:Linux:*)
+	    echo ${UNAME_MACHINE}-unknown-linux-gnu
+	exit ;;
     alpha:Linux:*:*)
 	case `sed -n '/^cpu model/s/^.*: \(.*\)/\1/p' < /proc/cpuinfo` in
 	  EV5)   UNAME_MACHINE=alphaev5 ;;