option-parser: Make bools boolean

option-parser: Make bools boolean

When option-parser is confronted with a boolean option, have it write a
bool rather than treating the value as a pointer to an int32.

(lib)weston already heavily uses bool types internally, so this has the
nice side effect of eliminating quite a few local variables which only
existed as integer shadows of internal boolean variables.

Signed-off-by: Daniel Stone <daniels@collabora.com>