This moves the registry higher in the LLVM library dependency stack.
Every client of the target registry needs to link against MC anyway to
actually use the target, so we might as well move this out of Support.
This allows us to ensure that Support doesn't have includes from MC/*.
Differential Revision: https://reviews.llvm.org/D111454
When reading 32 bits a 32-bit shift would be executed.
This is undefined behaviour, but in this case we can just replace the
entire scratch value to avoid it.
Differential Revision: https://reviews.llvm.org/D110769
