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Create a new channel as a copy of main.

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Delete channel

Delete main? This cannot be undone.

unwind-info.test
RUN: llvm-objdump --macho -u %p/Inputs/hello.obj.macho-x86_64 | FileCheck %s

CHECK: Contents of __compact_unwind section:
CHECK:   Entry at offset 0x0:
CHECK:     start:                0x0 _main
CHECK:     length:               0x3b
CHECK:     compact encoding:     0x01000000