Added cast of MB_CUR_MAX to size_t to silence compiler warning on

[nmh] / etc / rcvdistcomps.outbox

%(void(localmbox))%(void(width))%(putaddr Resent-From: )
%(lit)%(formataddr{addresses})\
%<(nonnull)%(void(width))%(putaddr Resent-To: )\n%>\
Resent-Fcc: outbox