[llvm] [NFCI][Globals] In GlobalObjects::setSectionPrefix, do conditional update if existing prefix is not equivalent to the new one. Returns whether prefix changed. (PR #158460)

[Mingming Liu via llvm-commits]

mingmingl-llvm wrote:

Created a re-land in https://github.com/llvm/llvm-project/pull/159161, test passes locally, so I enabled auto-merge -- the PR will reland if windows and Linux tests pass.

https://github.com/llvm/llvm-project/pull/158460