Add options to make elf symbol changes as warnings.

Some elf symbols in the .dynsym table of an .so file may not be present
in the headers exported by a shared library. We must still know about
these changes. Therefore, add options to make notifications about
these changes warnings instead of errors.

Bug: 62060883

Test: tests/test.py pass

Change-Id: Ic0cbad3370597c251f9e2c0f2b8cbb089aed155f