accel/tcg: cache single instruction TB on pending replay exception

accel/tcg: cache single instruction TB on pending replay exception

Again there is no reason to jump through the nocache hoops to execute
a single instruction block. We do have to add an additional wrinkle to
the cpu_handle_interrupt case to ensure we let through a TB where we
have specifically disabled icount for the block.

As the last user of cpu_exec_nocache we can now remove the function.
Further clean-up will follow in subsequent patches.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210213130325.14781-18-alex.bennee@linaro.org>