common: New functions timegm_u64, isotime2epoch_u64.
* common/mischelp.c (timegm): Move to ... * common/gettime.c (timegm): here. On Windows use timegm_u32. (timegm_u32): New. (isotime2epoch): Factor code out to ... (isotime_make_tm): new helper. (isotime2epoch_u64): New. (_win32_timegm): Remove duplicated code. (parse_timestamp): Use of timegm. (scan_isodatestr): Fallback to isotime2epoch_u64.
This mainly helps on 32 bit Windows. For Unix we assume everyone is
using 64 bit or shall wait until the libc hackers finally provide a
time64_t.
- GnuPG-bug-id: T6736