ubuntu-cpc: Refactor arch handling to fix armhf

[ Steve Langasek ]
  * Refactor some non-idiomatic architecture handling in
    live-build/ubuntu-cpc/hooks/999-cpc-fixes.chroot that also misidentifies
    the architecture name for armhf.

debian/changelog

@@ -1,3 +1,12 @@
+livecd-rootfs (2.209.11) trusty; urgency=medium
+
+  [ Steve Langasek ]
+  * Refactor some non-idiomatic architecture handling in
+    live-build/ubuntu-cpc/hooks/999-cpc-fixes.chroot that also misidentifies
+    the architecture name for armhf.
+
+ -- Robert C Jennings <robert.jennings@canonical.com>  Tue, 23 May 2017 21:38:47 -0500
+
 livecd-rootfs (2.209.10) trusty; urgency=medium
 
   [ Steve Langasek ]

live-build/ubuntu-cpc/hooks/999-cpc-fixes.chroot

@@ -126,26 +126,26 @@ fi
 
 #### END COMMON ARCH FUNCTIONS
 
-if [ "$arch" = "ppc64el" ]; then
-   add_serial_console hvc0
-   exit 0
-fi
-
-# ARM images are special
-if [[ "$arch" =~ (arm|arm64|aarch64) ]]; then
-
-   echo "Configuring ARM Serial Port"
-   add_serial_console ttyAMA0
-
-   echo "Image architecture is ARM. Existing vmbuilder-fixups"
 
-   exit 0
-fi
-
-## Add ttyS0 for i386/amd64 for Trusty and newer
-if [ "$arch" = "i386" -o "$arch" = "amd64" ]; then
-   add_serial_console ttyS0
-fi
+case $arch in
+	# ARM images are special
+	armhf|arm64)
+		echo "Configuring ARM Serial Port"
+		add_serial_console ttyAMA0
+
+		echo "Image architecture is ARM. Existing vmbuilder-fixups"
+
+		exit 0
+		;;
+	## Add ttyS0 for i386/amd64 for Trusty and newer
+	i386|amd64)
+		add_serial_console ttyS0
+		;;
+	ppc64el)
+		add_serial_console hvc0
+		exit 0
+		;;
+esac
 
 psuedo_grub_probe() {
    cat <<"PSUEDO_GRUB_PROBE"