Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

reloc-half.test
RUN: llvm-objdump -r %p/Inputs/reloc-half.obj.macho-arm | FileCheck %s

CHECK-DAG: 00000004 ARM_RELOC_HALF :upper16:(_stringbuf)
CHECK-DAG: 00000000 ARM_RELOC_HALF :lower16:(_stringbuf)