getopt: improve help text; code shrink

function                                             old     new   delta
generate_output                                      356     351      -5
packed_usage                                       29271   29257     -14

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
ps: seconds_since_boot: uint64_t -> ulong

Even if long is 32-bit, 4 billion second uptime isn't likely :)

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Merge remote-tracking branch 'bb/master' into sm-jb-mr1-wip