fpu: Pass float_status to floatx80_is_infinity()

fpu: Pass float_status to floatx80_is_infinity()

Unlike the other float formats, whether a floatx80 value is
considered to be an Infinity is target-dependent.  (On x86 if the
explicit integer bit is clear this is a "pseudo-infinity" and not a
valid infinity; m68k does not care about the value of the integer
bit.)

Currently we select this target-specific logic at compile time with
an ifdef.  We're going to want to do this at runtime, so change the
floatx80_is_infinity() function to take a float_status.

This commit doesn't change any logic; we'll do that in the
next commit.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250224111524.1101196-5-peter.maydell@linaro.org