Add ro.build.system_root_image

ro.build.system_root_image is true if the root directory is built
into the system image.

Change-Id: I17208ebd004c63aebb09db6c3e5f795619e73bd2
diff --git a/core/Makefile b/core/Makefile
index 31cef3f..8ef0e39 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -203,6 +203,7 @@
 			BUILD_ID="$(BUILD_ID)" \
 			BUILD_DISPLAY_ID="$(BUILD_DISPLAY_ID)" \
 			BUILD_NUMBER="$(BUILD_NUMBER)" \
+			BOARD_BUILD_SYSTEM_ROOT_IMAGE="$(BOARD_BUILD_SYSTEM_ROOT_IMAGE)" \
 			PLATFORM_VERSION="$(PLATFORM_VERSION)" \
 			PLATFORM_SECURITY_PATCH="$(PLATFORM_SECURITY_PATCH)" \
 			PLATFORM_BASE_OS="$(PLATFORM_BASE_OS)" \
diff --git a/tools/buildinfo.sh b/tools/buildinfo.sh
index 5c199b8..1329be7 100755
--- a/tools/buildinfo.sh
+++ b/tools/buildinfo.sh
@@ -20,6 +20,9 @@
 echo "ro.build.host=`hostname`"
 echo "ro.build.tags=$BUILD_VERSION_TAGS"
 echo "ro.build.flavor=$TARGET_BUILD_FLAVOR"
+if [ -n "$BOARD_BUILD_SYSTEM_ROOT_IMAGE" ] ; then
+  echo "ro.build.system_root_image=$BOARD_BUILD_SYSTEM_ROOT_IMAGE"
+fi
 echo "ro.product.model=$PRODUCT_MODEL"
 echo "ro.product.brand=$PRODUCT_BRAND"
 echo "ro.product.name=$PRODUCT_NAME"