[J-core] qemu updates / roadmap

[Christopher Friedt]

As it turns out, the reason that the variable was being read back as 0
was due to the linker script (boot/linker/sh32.x) not having the
correct location for ram0 (it turned out to be in a completely
unmapped section of memory - i.e. not in rom and not in sdram @
0x10000000).

I'd be happy to correct the mistakes in the linker script too, but it
might be best to have some other commentary first. I tend to be very
particular about my custom linker scripts to ensure that (rw) data is
properly relocated from rom to ram. I use a couple of extra variables
for that which likely aren't in the usual crt initialization.

I haven't yet examined the bootrom crt initialization yet, so I'll do
that first before i post anything w.r.t. linker script modifications.

Luckily, at least this test is passing, so it would appear (for now)
that the existing qemu pipeline is intact.