devtool: fix build env command execution error handling
If we execute an external command, we ought to prepare for the
possibility that it can fail and handle the failure appropriately. We
can especially expect this to happen when running bitbake in this
scenario. Ensure we return the appropriate exit code to the calling
process.
Fixes [YOCTO #7757].
(From OE-Core master rev:
98a716d79bfc5434a5b42d3ca683eab3eea30a41)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
