[llvm] [X86] Check if signed value is too large for fixup under some conditions (PR #150976)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

> In `X86AsmBackend::applyFixup`, the assert in the else branch is reachable for out-of-range fixup values and should be fixed. `FK_Data_[1248]` may have true of false PCRel, while other fixup kinds have a known PCRel value.
> 
> When `IsResolved`, we should add the reportError check for more fixup kinds, but should ensure every new case has test coverage.

@MaskRay was this answered to your satisfaction? 

https://github.com/llvm/llvm-project/pull/150976