Add missing tests for build attribute encodings in object files.

test/MC/ARM/directive-eabi_attribute.s was missing several tests of object file
encodings relative to the existing tests for assembly file encodings. This
commit adds the missing tests.

Change-Id: Ie110ca02b65e8f4d4c77f437bd09d03607fa5c0d

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221250 91177308-0d34-0410-b5e6-96231b3b80d8