utils/docker-run: bind mount .git/objects if needed

If buildroot is checked out as part of a 'repo' manifest, docker-run
doesn't fully bind mount the .git directory, leading to commands such
as `utils/docker-run make check-package` to fail.

Signed-off-by: Nicolas Boichat <drinkcat@google.com>
[yann.morin.1998@free.fr: use newly introduced mountpoints list]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

utils/docker-run

@@ -33,6 +33,14 @@ if [ "${GIT_DIR}" ]; then
     # path already (in a wordir), then that's a noop.
     GIT_DIR="$(cd "${MAIN_DIR}"; readlink -e "${GIT_DIR}")"
     mountpoints+=( "${GIT_DIR}" )
+
+    # 'repo' stores .git/objects separately.
+    if [ -L "${GIT_DIR}/objects" ]; then
+        # GITDIR is already an absolute path, but for symetry
+        # with the above, keep the same cd+readlink construct.
+        OBJECTS_DIR="$(cd "${MAIN_DIR}"; readlink -e "${GIT_DIR}/objects")"
+        mountpoints+=( "${OBJECTS_DIR}" )
+    fi
 fi
 
 if [ "${BR2_DL_DIR}" ]; then