TCF Agent: Copy machine/arm to armv6l for work on Raspberry Pi
TCF Agent: [404253] debug: initial armv6l stepping emulation

Added initial software emulation for single-stepping.
This requires computing the next address for each instruction,
and planting a breakpoint there. The next-address computation
is incomplete at this time, but should work for basic debugging.
See https://bugs.eclipse.org/bugs/show_bug.cgi?id=404253
for details and discussion.
update cpu_disable_stepping mode prototype