r221915 changed a number of asserts into error-checks in MachOObjectFile, but no test-cases were added. Malformed objects covering the following cases should be tested: (1) Duplicate SymtabLoadCmd. (2) Duplicate DysymtabLoadCmd. (3) Duplicate DataInCodeLoadCmd. (4) Duplicate DyldInfoLoadCmd. (5) Duplicate UuidLoadCmd. At a minimum we can test that llvm-objdump no longer asserts on these cases. Once we have some proper error reporting we can check specifically for that.