This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
DE_UPDATE was confused with DE_MODIFIED in some places (they do have
confusing names). Handle them exactly the same as IN_UPDATE and
IN_MODIFIED. This fixes chmod() and chown() clobbering the mtime
and other bugs.
DE_MODIFIED was set but not used.
Parenthesize macro args.
DE_TIMES() now takes a timeval arg instead of a timespec arg. It was
stupid to use a macro for speed and do unused conversions to prepare
for the macro.
Restore the left shifting of the DOS seconds count by 1. It got
lost among the shifts for the bitfields, so DOS seconds counts
appeared to range from 0 to 29 seconds (step 1) instead of 0 to 58
seconds (step 2).
Actually use the passed-in mtime in deupdat() as documented so that
utimes() works.
Change `extern __inline's to `static inline's so that msdosfs_fat.o
can be linked when it is compiled without -O.
Remove faking of directory mtimes to always be the current time. It's
more surprising for directory mtimes to change when you read the
directories than for them not to change when you write the directories.
This should be controlled by a mount-time option if at all.
