[llvm] [BOLT][RISCV] Handle static IFUNC calls through .iplt (PR #207733)

[via llvm-commits]

Thrrreeee wrote:

> Smaller, focused PRs are easier to review and usually receive feedback more quickly.

I will split the changes into multiple PRs for upstreaming. This PR will focus on IPLT support first, followed by the GNU ld issue mentioned by @WangJee, and RV32 support in a subsequent PR.

https://github.com/llvm/llvm-project/pull/207733