Extend the CPU ABI specification mechanism.

Add a (read only) system property that is a comma
separated list of ABIs supported by the device in order
of preference. For example, typical arm-v8 device might
define:

ro.cpu.abilist = arm64-v8a,armeabi-v7a,armeabi

For most purposes, a single flattened list like the above is
probably more useful than the parallel system of variables
TARGET_CPU_ABI{2} / TARGET_2ND_ARCH_CPU_ABI{2} that we use
in the build system.

Change-Id: If9102669ad9f5f8fd89a8bcc5bf88cca1acadc3c

tools/buildinfo.sh

@@ -20,10 +20,17 @@ echo "ro.product.brand=$PRODUCT_BRAND"
 echo "ro.product.name=$PRODUCT_NAME"
 echo "ro.product.device=$TARGET_DEVICE"
 echo "ro.product.board=$TARGET_BOOTLOADER_BOARD_NAME"
+
+# These values are deprecated, use "ro.product.cpu.abilist"
+# instead (see below).
+echo "# ro.product.cpu.abi and ro.product.cpu.abi2 are obsolete,"
+echo "# use ro.product.cpu.abilist instead."
 echo "ro.product.cpu.abi=$TARGET_CPU_ABI"
 if [ -n "$TARGET_CPU_ABI2" ] ; then
   echo "ro.product.cpu.abi2=$TARGET_CPU_ABI2"
 fi
+echo "ro.product.cpu.abilist=$TARGET_CPU_ABI_LIST"
+
 echo "ro.product.manufacturer=$PRODUCT_MANUFACTURER"
 if [ -n "$PRODUCT_DEFAULT_LANGUAGE" ] ; then
   echo "ro.product.locale.language=$PRODUCT_DEFAULT_LANGUAGE"