Address objtool check failures in lua module

The use of void attribute((noreturn)) in kernel builds
was causing lots of warnings if CONFIG_STACK_VALIDATION
is active. For now we just remove this attribute to achieve
clean builds for the Lua module. There was no significant
increase in the time to run the full channel_program ZTS tests.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Don Brady <don.brady@delphix.com>
Closes #7173