Commonalize typical [b,]k,m suffix struct

function                                             old     new   delta
bkm_suffixes                                           -      32     +32
static.km_suffixes                                    24       -     -24
suffixes                                              32       -     -32
static.bkm                                            32       -     -32
head_tail_suffixes                                    32       -     -32
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(add/remove: 2/6 grow/shrink: 0/0 up/down: 72/-160)           Total: -88 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
typo fix in comment

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