Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

stabs.test
# RUN: llvm-objdump --syms %p/Inputs/macho-stabs-x86_64
# RUN: llvm-objdump -D %p/Inputs/macho-stabs-x86_64
# REQUIRES: x86-registered-target