Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r264620:
Fix typo.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Use ISO C99 integer types in sys/kern where possible.

There are only about 100 occurences of the BSD-specific u_int*_t
datatypes in sys/kern. The ISO C99 integer types are used here more
often.

Better naming of fattime conversion functions, they do convert to timespec
after all.

Add 'utc' argument to control if fattimestamps are on UTC or local timezone
calendar.

Add two new functions to convert FAT filesystem format timestamps
to and from struct timespec, to replace the crummy conversion
function which have been copy&pasted into three different
filesystems already.

Apart from general crummyness as indicated by code like:

for (year = 1970;; year++) {
inc = year & 0x03 ? 365 : 366;
if (days < inc)
break;
days -= inc;
}

They also contain specialized crummyness which tries to compensate
for the general crummyness by caching recent conversion results,
with no regard for locking or consistency.

These replacement functions are smaller, O(1) and handle the Y2.1K
leap-year correctly.

Ideally, these functions should live in a module of their own,
which the three offending filesystems would depend on, but the
size is 877 bytes of code (on i386), so that would be false
economy.