lacp: Use C99 bool for boolean return value

This improves readability.

No functional change intended.

MFC after: 1 week

(cherry picked from commit 5a8abd0a298e6e7a8bf938a7eb171b647b1860cd)
(cherry picked from commit d1d5d8f69659c4d3573e64a62a9306ee944d9e4d)