[NativeAOT/x86] Enable SAFESEH

[jkotas]

Repro

Build repro/reproNative convenience project for win x86 target (https://github.com/dotnet/runtime/blob/main/docs/workflow/building/coreclr/nativeaot.md)

Result

1>repro.obj : error LNK2026: module unsafe for SAFESEH image.
1>Runtime.WorkstationGC.lib(AllocFast.asm.obj) : error LNK2026: module unsafe for SAFESEH image.
1>Runtime.WorkstationGC.lib(WriteBarriers.asm.obj) : error LNK2026: module unsafe for SAFESEH image.
1>Runtime.WorkstationGC.lib(ExceptionHandling.asm.obj) : error LNK2026: module unsafe for SAFESEH image.
1>Runtime.WorkstationGC.lib(GcProbe.asm.obj) : error LNK2026: module unsafe for SAFESEH image.
1>Runtime.WorkstationGC.lib(StubDispatch.asm.obj) : error LNK2026: module unsafe for SAFESEH image.
1>Runtime.WorkstationGC.lib(MiscStubs.asm.obj) : error LNK2026: module unsafe for SAFESEH image.
1>Runtime.WorkstationGC.lib(PInvoke.asm.obj) : error LNK2026: module unsafe for SAFESEH image.
1>Runtime.WorkstationGC.lib(UniversalTransition.asm.obj) : error LNK2026: module unsafe for SAFESEH image.
1>C:\runtime\src\coreclr\tools\aot\ILCompiler\reproNative\Release\reproNative.exe : fatal error LNK1281: Unable to generate SAFESEH image.

The reproNative project has the secure vcproj defaults, passes /SAFESEH to the linker and linker complains that the inputs are not annotated with SAFESEH.

We should get the obj inputs annotated correctly (looks like it will require change in the obj writer) and pass SAFESEH to the linker on win-x86 to avoid compliance warnings from tools like https://github.com/microsoft/binskim

[jkotas]

cc @filipnavara

[filipnavara]

The ObjWriter change should be quite trivial. We just need to emit the @feat.00 symbol and we already do a very similar thing for control flow guard.