Fix bug where std.math.asinh64 doesn't respect signedness for negative values (#9940)
Fix bug where std.math.asinh64 doesn't respect signedness for negative values (#9940)

* std: Correct math.asinh64 to return correct signedness for negative values

* std: Add tests for negative values for math.asinh32 and math.asinh64
andrewrk/zig,andrewrk/zig