bsd-user: Add '-one-insn-per-tb' option equivalent to '-singlestep'

bsd-user: Add '-one-insn-per-tb' option equivalent to '-singlestep'

The '-singlestep' option is confusing, because it doesn't actually
have anything to do with single-stepping the CPU. What it does do
is force TCG emulation to put one guest instruction in each TB,
which can be useful in some situations.

Create a new command line argument -one-insn-per-tb, so we can
document that -singlestep is just a deprecated synonym for it,
and eventually perhaps drop it.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20230417164041.684562-6-peter.maydell@linaro.org