strptime() is an XPG4v2 function, on OpenBSD the prototype
is not included in time.h unless visibility is set, it needs
either "#define _XOPEN_SOURCE_EXTENDED 1" or _XOPEN_SOURCE
>= 500. Without this the prototype isn't included and
strptime's returned pointer is truncated to an int, causing
SEGV on 64-bit arches when using it.
Thanks @sthen