Fix uninitialized variable usage.

If the dladdr call fails, then info.dli_fname will be unitialized.
Make sure that this can't happen.

Bug: 32907235

Test: Enabled malloc debug on an angler and verified that function names
Test: still work.
Change-Id: I738e66d9f37bce07bc4c10f1f9bac11fbfdae2c7