This makes output a bit shorter and nicer. For us, shorter output is generally
better.
Also, drop unnecessary UINT64_C macros. The left operand is always uint64_t,
and C upcasting rules mean that it doesn't matter if the right operand is
narrower or signed, the operation is always done on the wider unsigned type.
Also,
- drop unnecessary +1 from buffer size, as IF_NAMESIZE or IFNAMSIZ
includes the nul at the end.
- format_ifname() does not update buffer on failure,
- introduces format_ifname_alloc(), FORMAT_IFNAME(), and their friends.
According to Coverity, 194 ouf of 227 times we check for snprintf return code.
Voidify the rest.
CID#1461512
CID#1461513
CID#1461514
CID#1461515
CID#1461516
CID#1461518
CID#1461519
CID#1461520
CID#1461522
