configure: add [lm32|unicore32]-softmmu to deprecation logic

While we are at it move the few places where they are into the
deprecation build bucket.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200915134317.11110-9-alex.bennee@linaro.org>