[llvm-readobj] - Remove excessive `dynamic.test`

dynamic.test is a test that checks dumping of
dynamic tags. It uses precompiled objects as inputs
and it is completely excessive nowadays:

Now we have elf-dynamic-tags-machine-specific.test
and elf-dynamic-tags.test. 
(https://github.com/llvm-mirror/llvm/blob/master/test/tools/llvm-readobj/elf-dynamic-tags-machine-specific.test)
(https://github.com/llvm-mirror/llvm/blob/master/test/tools/llvm-readobj/elf-dynamic-tags.test)

First is used to check target specific tags and second tests the common flags.
These tests use YAML, which is much better than using precompiled binaries.

Note that new reviews tend to update the YAML based
tests to add new tags, e.g. see D62596.

With this patch it became possible to remove
dynamic-table-so.aarch64 binary from the inputs folder.
(other binaries are still used in other tests).

Differential revision: https://reviews.llvm.org/D62728

llvm-svn: 362224