Add -ffp-contract=off for Clang 14 and later

Summary

Clang 14 changed its floating-point behavior. Now the default is -ffp-contract=on even with -O0

Steps to reproduce

FMA is enabled by default for Clang 14 and later. This doesn't seem like an issue for x86 (because of different CPU instructions to do FMA), but for arm64 things like libsampling can easily fail.

Example case

tutorials/incompressible/simpleFoam/backwardFacingStep2D leads to infinite loop when running the sample function.

What is the current bug behaviour?

A lot of tutorial cases using libsampling will be trapped in infinite loop. Any code related to computational geometry may get unexpected results.

What is the expected correct behavior?

The floating-point calculation should strictly follow IEEE-754 to avoid any potential bug that is almost impossible to debug.

Relevant logs and/or images

https://releases.llvm.org/14.0.0/tools/clang/docs/ReleaseNotes.html#floating-point-support-in-clang

Environment information

• OpenFOAM version : Any
• Operating system : Any
• Hardware info : Most likely affecting arm64
• Compiler : Clang 14 and later

Possible fixes

I don't know if it's possible to add flags in wmake rules based on compiler version. I would propose add -ffp-contract=off explicitly to the general Clang wmake rule as it doesn't change anything before Clang 13. For Arm and Fujitsu, it should be added automatically.