yopts: Export yopts_realloc to program

Signed-off-by: Pavel Emelyanov <xemul@sacred.ru>
yopts: Export enerated usage fn to program

Signed-off-by: Pavel Emelyanov <xemul@sacred.ru>
yopts: Reshuffle and sanitize static functions

Get rid of forward declarations when not required and
remove the ${PROJ}_ prefix from what is not exported.

Signed-off-by: Pavel Emelyanov <xemul@sacred.ru>