Using int was a mistake. This patch changes String, StringImpl,
StringView and StringBuilder to use size_t instead of int for lengths.
Obviously a lot of code needs to change as a result of this.
The former allows you to inspect the string while it's being built.
It's an explicit method rather than `operator StringView()` because
you must remember you can only look at it in between modifications;
appending to the StringBuilder invalidates the StringView.
The latter lets you clear the state of a StringBuilder explicitly, to
start from an empty string again.
We should work towards a pattern where we take StringView as function
arguments, and store String as member, to push the String construction
to the last possible moment.
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
You're never gonna be right 100% of the time when guessing how much buffer
space you need. This avoids having to make that type of decision in a bunch
of cases. :^)
Okay, now ProcFS doesn't crash due to the crappy buffer size estimates
not really working out. This thing has dogshit performance and I will
fix that separately.
The SpinLock was all backwards and didn't actually work. Fixing it exposed
how wrong most of the locking here is.
I need to come up with a better granularity here.
