[llvm] [RISCV][GlobalISel] Select G_GLOBAL_VALUE (PR #70091)

[Jessica Clarke via llvm-commits]

jrtc27 wrote:

isPositionIndependent() needs to use LLA/LGA as appropriate based on whether the symbol is local. Plus -mcmodel=medium needs to use LGA for extern weak. See RISCVTargetLowering::getAddr for the full set of behaviours needed.

https://github.com/llvm/llvm-project/pull/70091