target/sh4: Introduce CHECK_FPSCR_PR_*

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-Id: <20170718200255.31647-23-rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
