classes/populate_sdk_ext: force a known value for TMPDIR
If TMPDIR is configured to be somewhere outside of TOPDIR (a not
uncommon configuration where you have multiple disks and space on /home
is at a premium) then our attempt to find out the location of paths
under TMPDIR by using a relative path led to horribly broken paths
ending up in the eSDK. To save pain, just force a known value for TMPDIR
(i.e. ${TOPDIR}/tmp) and then we can assume that everywhere else.
Fixes [YOCTO #10797].
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
