Moves some timing func from benchutil to parlib

They don't need to be in benchutil, unlike the other benchutil functions
that use libm.  Also, programs that want to use the simply timing
functions won't need to -lbenchutil (and -lm).
Make ndblib not reopen and reread files all the time.

Sadly, stat(2) returns 0 for mtime still. So we've got some
nasty hacks in here to make sure we only read files once. We'll
need to come back to this or better yet rewrite this mess in Go.
It's the 21st century and it's silly not to cache everything, and
it's super silly to write code like this in C.

Result:
cs&
mount -a '#s/cs' /net
csquery /net/cs tcp!localhost!22

The first time, it is slow, as it is now. Subsequent
csquery commands, if it hits the cache, are quite fast,
basically intantaneous, even in qemu.
This should make go test much more palatable.

Signed-off-by: Ronald G. Minnich <rminnich@google.com>
Fixes stat() #include
Fixes getfields()

The main for loop steps through rune (characters).  I don't know what
the intent of 'next' was, but since the loop already managed the
character/rune length, 'next' could only offset us farther into the
rune.
Fixes MAC and arp printing

Can now cat /net/arp.  The spacing is still off for the %I, but at least
we can see the info.
Merge branch 'master' of github.com:brho/akaros into testing