Update docs to say that a FunctionPass should not inspect other functions than the one being processed.
Please let me know if you disagree with this assessment (no one has yet, after asking on llvm-commits and LLVMDev) and I will revert.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185848 91177308-0d34-0410-b5e6-96231b3b80d8