[amdgpu] libspirv: Fix pushRegion

[Macdu]

Fix an issue with the pushRegion function, which modifies/duplicates (in a way that leads to undefined behavior) the id definitions and uses of its own fields instead of adding the ones from the other region.

[DHrpcs3]

Whole shader part already rewritten, but not uploaded yet. Please do not try to find bugs at gpu side, there would be big changes soon Thank you for your findings anyway