target/ppc: Move float_check_status from FPU_FCTI to translate

target/ppc: Move float_check_status from FPU_FCTI to translate

Fixes a bug in which e.g XE enabled causes inexact to be raised
before the writeback to the architectural register.

All of the users of GEN_FLOAT_B either set set_fprf, or are one
of the convert-to-integer instructions that require this behaviour.
Split out the two gen_helper_* calls in gen_compute_fprf_float64
and protect only the first with set_fprf.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211119160502.17432-12-richard.henderson@linaro.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>