Add Linux powerpc64le and powerpcle entries.

Stopgap to resolve bz#2409 because we are so close to release and will
update config.guess and friends shortly after the release.  ok djm@

config.guess

@@ -982,6 +982,12 @@ EOF
     ppc:Linux:*:*)
 	echo powerpc-unknown-linux-gnu
 	exit ;;
+    ppc64le:Linux:*:*)
+	echo powerpc64le-unknown-linux-gnu
+	exit ;;
+    ppcle:Linux:*:*)
+	echo powerpcle-unknown-linux-gnu
+	exit ;;
     s390:Linux:*:* | s390x:Linux:*:*)
 	echo ${UNAME_MACHINE}-ibm-linux
 	exit ;;