[llvm-readobj][test] - Cleanup hash-histogram.test

In this test case we use 3 precompiled objects to
test how we print a histogram for an GNU hash section.
It does not make sense to use precompiled objects
for that. Also we could have 2 tests: one for 32 and
another for 64 bits target.

This patch does this change. It is not possible to remove
these precompiled objects because they are used elsewhere.

Differential revision: https://reviews.llvm.org/D71606