libbb/procps: smaller global data for username/groupname cache

function                                             old     new   delta
get_cached                                           101     133     +32
cache_user_group                                       -       4      +4
get_cached_username                                   17      14      -3
username                                               8       -      -8
groupname                                              8       -      -8
clear_username_cache                                  65      47     -18
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(add/remove: 1/2 grow/shrink: 1/2 up/down: 36/-37)             Total: -1 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1 file changed