configure: Decouple target directory from base architecture

So far we have had an architecture ppc64 have a base architecture ppc
and reuse its source directory target-ppc/.

Allow using a differently named directory and default to the base
architecture for backwards compatibility.

This flexibility is handy when the base architecture starts with a digit
and is thus unsuited for C identifiers.

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
target-rl78: Add initial stubs for RL78

Add support for {78k0,rl78}-softmmu in configure.
Stub out target-rl78/ and hw/rl78/.

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
rl78: Prepare Renesas RL78/G13 Promotion Board

Set up RAM and code flash.

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Add ELF machine identifier

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
rl78: Load BIOS

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Flesh out disas

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Implement reset

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Implement tlb_fill()

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Add calls to gen_io_{start,end}()

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Add call to tcg_gen_debug_insn_start()

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Update PC

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
rl78: Defer CPU realization til after BIOS is loaded

On reset the CPU needs to load PC from memory.
Therefore inline cpu_rl78_init() into machine init.

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Load reset vector to PC

Inspired by ARM M profile. Thanks to Peter for suggesting.

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Implement MOV !addr16,#byte

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
rl78: Add SFR MemoryRegion

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
rl78: Add MemoryRegion for GPRs

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Implement MOVW sfrp,#word

This is the first instruction of GCC-generated _start, thus starting to
make target-rl78 "usable".

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Prepare SP

Prepare TCG variable and add to info output.

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Implement MOV ES,#byte

Introduce ES and CS.

Signed-off-by: Andreas Färber <andreas.faerber@web.de>
target-rl78: Prepare 2nd MAP

Signed-off-by: Andreas Färber <andreas.faerber@web.de>