bootrom: Some corrections from Manuel Pazos

Plus some tidying of them to match the sdcc assembler

Still doesn't work but its hopefully closer now
fuzix: break out execve()

We need to split this into pieces and also allow some of it to be
cpu specific
syscall_exec: use staticfast to shave 0.5K off execve()
process: fix ACCT build
vt: Don't assume char is signed (next sdcc will change this, 6502 isnt)
usermem: const v const pointer compares

Remove warnings (cc65 is overly pedantic)
cpu: push time_t into CPU dependencies
6502: unbitrot
single: fix types
swap: correct sign of pointers
m6809test: Switch t using lwlink directly and fix some oddments

This allows us to actually control memory the way we need
dragon: Initial bits towards a Dragon64 port of sorts

That's if you count replacing the boot ROMs as a "port"
idump: We don't want the debugging in discard !
syscall_other: Fix bracketing
banking: lay the groundwork

Unfortunately the current m6809 gcc build banking support is broken and
doesn't remember to add the bank names with the .db for the bank so it fails
to assemble.

Uglies:
- We put all syscalls in the same bank to avoid having to have a 'far' pointer
  form for the syscall table
- We don't do this for devices, so will need to rig up some far pointer
  hackery for this
6809: bank names should be strings
tty: Group objects together so the compiler can use one pointer register

Takes 100 bytes off tty_inproc alone
Removed implicit ints in mkfs.c

Some functions have return type int implicitly, which is forbidden by C99. This commit corrects them.
Merge pull request #13 from erkinalp/master

Removed implicit ints in mkfs.c
dragon,devtty: mask chars for braindead video