target/i386: Avoid using floatx80_infinity global const

target/i386: Avoid using floatx80_infinity global const

The global const floatx80_infinity is (unlike all the other
float*_infinity values) target-specific, because whether the explicit
Integer bit is set or not varies between m68k and i386.  We want to
be able to compile softfloat once for multiple targets, so we can't
continue to use a single global whose value needs to be different
between targets.

Replace the direct uses of floatx80_infinity in target/i386 with
calls to the new floatx80_default_inf() function. Note that because
we can ask the function for either a negative or positive infinity,
we don't need to change the sign of a positive infinity via
floatx80_chs() for the negative-Inf case.

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: 20250224111524.1101196-4-peter.maydell@linaro.org
Message-id: 20250217125055.160887-4-peter.maydell@linaro.org