Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

cstring.ll
; RUN: llc < %s -mtriple=i386-apple-darwin | FileCheck %s
; rdar://6479858

; CHECK-NOT: comm
@str1 = internal constant [1 x i8] zeroinitializer