llvm-objdump: return non-zero exit code for certain cases of invalid input

* If the input file is missing;
* If the type of input object file can't be recognized;
* If the object file can't be parsed correctly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239065 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed