[llvm] TargetMachine: Remove pointer-size query methods (PR #226404)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> rv64ilp32

This should be changed by the triple, like how x32 handles this. 

> a property of ABI.

Really the ABI should be fully computable from the triple alone. The ABI name is a really pervasive hack that really should have been encoded or implied directly in the triple 

https://github.com/llvm/llvm-project/pull/226404