Implement GcInfo v2 for X86

Implement GcInfo v2 for X86

This commit includes the following changes:
1) Thread GcInfo version through X86 specific APIs
2) Add ReturnKind and ReversePinvokeOffset fields to InfoHdr structure
   GcInfo v1 and v2 use the same InfoHdr structures, because:
   InfoHdrSmall: ReturnKind is encoded within previously unused bits.
   InfoHdr: revPInvokeOffset will never be written to the image,
            since ReversePinvokeOffset==INVALID_REV_PINVOKE_OFFSET for V1.
3) Update the Pre-computed header table to include bits for the above
   [The default setting of ReturnKind=RT_Scalar is used for all entries in the table.
    Optimizing this table based in most frequent usage scenarios is to be done separately]
4) Change the GC encoder/decoder to handle the above two fields
5) Use the ReturnKind in the GCInfo from thread-suspension code.

GcInfo version is changed for CoreCLR X86 only, not for Desktop JIT
Fixes dotnet/coreclr#4379

Commit migrated from https://github.com/dotnet/coreclr/commit/4871121dbb7d1ee3282f9beb950cd73fb4f8a95b