sstate.bbclass: check if mirror directory is writable
Commit
51edde653707e7a3cd2186082458f01f32cd1996 makes a wrong assumption
that SSTATE_MIRRORS have write permissions.
A mirror is by definition outside of it's user control. In my use case
it happens I does not have permissions to update the access time of the
dereferenced symbolic-link file.
Checked if file is writable before changing its atime.
Thanks to Paulo Neves for the patch.
[YOCTO #11307]
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
