QEMU i386 fldl instruction is affected by the precision control bits of the FPU control word
Description of problem:
~~The QEMU softfloat float64_to_floatx80 implementation is broken and does not produce correct results.~~ QEMU i386 fldl instruction is affected by the precision control bits of the FPU control word.

```
IN = 1234.567890 (0x40934a4584f4c6e7)
OUT = 1234.567871 (0x40099a522c0000000000)
```

This bug was introduced in the QEMU commit qemu/qemu@8ae5719 as part of the switchover to FloatParts, and is still present in the latest tag (v7.0.0-rc4 as of now).

Prior to the offending commit:

```
IN = 1234.567890 (0x40934a4584f4c6e7)
OUT = 1234.567890 (0x40099a522c27a6373800)
```

This breaks the i386 emulation of `fldl st(0)` (`helper_fldl_ST0`).
Steps to reproduce:
Call `float64_to_floatx80` with the input value of `1234.567890 (0x40934a4584f4c6e7)` and see the returned result.
Additional information:
See https://github.com/zephyrproject-rtos/sdk-ng/issues/461