We accidentally threw exceptions previously

Turn off the logging by default.

Unless we are tracing or cosimulating, we should run for a long as
possible inside riscv_cpu_interp64().  This change speeds up normal
execution by a large amount.

Don't clear that bit as we have no path to turn it on again.  This
change enables output with interrupts enables (used to hang).  It's
still lacking periodic polling which is required for input to work.

Now by default Ctrl-C will not stop emulation but is sent to the guest.
To enable breaking out C-b is used as a prefix key:

  C-b h   print help
  C-b x   exit emulator
  C-b C-b send C-b

- Quell GCC warnings (by casting ignored return values)
- Fix `--dump_memories`; it never took an argument
- No Tabs in Source Code!
- Code clean up

The cmake crate requires this and it doesn't affect the current build

mmio range cfg/arg removed: any address access that isn't mem-mapped as virtIO or RAM is now propagated from DUT in cosim

Custom CSR hooks can now tell exactly which csr instruction were used

Replaced with a slightly less broken version

tdata3 is optional.  We should have a better way of supporting
different configurations, but it's safe to drop for now.

In order of severity
- claim access didn't work (word vs byte index confusion)
- 0-based/1-based confusion cased pending to not match actual irq
- reading claim must clear the pending interrupt
- disabled sources still triggered
- context assignement wasn't respected
- contexts weren't being distinguished
- VIRTIO_IRQ assignment clashing with hardwired devices

Note, this is the minimal change I could make to get it fixed.  It
still doesn't handle priorities and the code is in desperate need of
restructuring (and name fixing).  The PLIC in QEMU (sifive_plic.c) is
very clean and should be use as gold standard.

To make this slightly easier to build, don't depend of standard
headers as they aren't present by default for some cross tool chains.

Signed-off-by: damageboy <125730+damageboy@users.noreply.github.com>

Signed-off-by: damageboy <125730+damageboy@users.noreply.github.com>

Use intrinsic clz for bitcounting. While clz is not available, use
branchless implementation instead.

Commit d8689621 slipped in an presumedly unintential enable of dumping
the DTB