Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

upgrade-global-ctors.ll
; RUN:  llvm-dis < %s.bc| FileCheck %s
; RUN:  verify-uselistorder < %s.bc

; The 2-field form @llvm.global_ctors will be upgraded when reading bitcode.
; CHECK: @llvm.global_ctors = appending global [0 x { i32, void ()*, i8* }] zeroinitializer