[llvm] [BOLT][BTI] Disassemble PLT entries when processing BTI binaries (PR #169663)

[Maksim Panchenko via llvm-commits]

maksfb wrote:

Currently, there's a bespoke support for PLT functions where they are disassembled in `RewriteInstance` and then analyzed in `MCPlusBuilder::analyzePLTEntry()`. I don't know the exact analysis you plan on the first instruction, but maybe it's possible within the existing analysis code by extending `analyzePLTEntry()` interface?

https://github.com/llvm/llvm-project/pull/169663