build_library: Place EXTRA_SYSEXTS in a separate file

This allows it to be sourced from other scripts and used e.g. in
generating an image changes summary.

Signed-off-by: Jeremi Piotrowski <jpiotrowski@microsoft.com>

build_image

@@ -104,6 +104,7 @@ fi
 . "${BUILD_LIBRARY_DIR}/dev_container_util.sh" || exit 1
 . "${BUILD_LIBRARY_DIR}/test_image_content.sh" || exit 1
 . "${BUILD_LIBRARY_DIR}/vm_image_util.sh" || exit 1
+. "${BUILD_LIBRARY_DIR}/extra_sysexts.sh" || exit 1
 
 PROD_IMAGE=0
 PROD_TAR=0

build_library/extra_sysexts.sh

@@ -0,0 +1,3 @@
+EXTRA_SYSEXTS=(
+  zfs:sys-fs/zfs
+)

build_library/prod_image_util.sh

@@ -248,10 +248,6 @@ create_prod_tar() {
   upload_image "${container}"
 }
 
-EXTRA_SYSEXTS=(
-  zfs:sys-fs/zfs
-)
-
 create_prod_sysexts() {
   local image_name="$1"
   local image_sysext_base="${image_name%.bin}_sysext.squashfs"