[x86/Linux] Disables FrameHandlerExRecordWithBarrier for non-Windows platforms

[parjong]

Currently, FrameHandlerExRecord is available only for Windows platform.

This commit disables FrameHandlerExRecordWithBarrier (which depends on FrameHandlerExRecord) for non-Windows platforms.

[parjong]

\CC @seanshpark

[janvorli]

@parjong I think that after we've decided to stop attempts to enable Unix AMD64 / ARM style exception handling (WIN64EXCEPTIONS symbol related stuff) at the moment, we should do this differently.
Revert the change that @seanshpark made to the excep.h some time ago that made portions of it, including the FrameHandlerExRecord, Windows only.

[parjong]

@janvorli Thanks you for comment. Then, should we port EXCEPTION_REGISTRATION_RECORD to PAL layer? While porting, I found many code that accesses the internals of this structure, but this structure currently has no definition.

[janvorli]

@parjong Yes, it seems like that would be a way of the least resistance. The structure is very simple:

typedef struct _EXCEPTION_REGISTRATION_RECORD {
    struct _EXCEPTION_REGISTRATION_RECORD *Next;
    PEXCEPTION_ROUTINE Handler;
} EXCEPTION_REGISTRATION_RECORD;

[janvorli]

We should put it to palrt.h close to the _DISPATCHER_CONTEXT - the PEXCEPTION_ROUTINE is defined there too.

[parjong]

@janvorli I submitted #8408, and it seems that adding EXCEPTION_REGISTRATION_RECORD makes it much easier to bring up x86/Linux build. Thank you!

[parjong]

I'll close this PR as #8409 also resolves this issue.