[spinel] change parsing of boolean (#2433)
[spinel] change parsing of boolean (#2433)

This commit brings/syncs the change in `spinel.c` from wpantund.
This change was done as part of wpantund commit d77e7cbf23 which
addressed some of the fuzzer test issues.
abtink/openthread,srickardti/openthread,abtink/openthread,openthread/openthread,xiaom-GitHub/openthread,librasungirl/openthread,abtink/openthread,mszczodrak/openthread,bukepo/openthread,jwhui/openthread,chshu/openthread,xiaom-GitHub/openthread,georgecpr/openthread,pvanhorn/openthread,jwhui/openthread,chshu/openthread,chshu/openthread,jwhui/openthread,turon/openthread,erja-gp/openthread,lanyuwen/openthread,gandreello/openthread,georgecpr/openthread,librasungirl/openthread,librasungirl/openthread,xiaom-GitHub/openthread,LeZhang2016/openthread,turon/openthread,turon/openthread,lanyuwen/openthread,chshu/openthread,turon/openthread,lanyuwen/openthread,openthread/openthread,xiaom-GitHub/openthread,lanyuwen/openthread,openthread/openthread,erja-gp/openthread,librasungirl/openthread,chshu/openthread,srickardti/openthread,georgecpr/openthread,mszczodrak/openthread,pvanhorn/openthread,abtink/openthread,lanyuwen/openthread,mszczodrak/openthread,srickardti/openthread,pvanhorn/openthread,pvanhorn/openthread,pvanhorn/openthread,LeZhang2016/openthread,xiaom-GitHub/openthread,erja-gp/openthread,gandreello/openthread,xiaom-GitHub/openthread,LeZhang2016/openthread,LeZhang2016/openthread,mszczodrak/openthread,mszczodrak/openthread,LeZhang2016/openthread,gandreello/openthread,mszczodrak/openthread,erja-gp/openthread,srickardti/openthread,gandreello/openthread,erja-gp/openthread,pvanhorn/openthread,bukepo/openthread,bukepo/openthread,georgecpr/openthread,gandreello/openthread,openthread/openthread,chshu/openthread,LeZhang2016/openthread,georgecpr/openthread,lanyuwen/openthread,bukepo/openthread,georgecpr/openthread,jwhui/openthread,gandreello/openthread,erja-gp/openthread