ossl_bsearch(): New generic internal binary search utility function

OBJ_bsearch_ and OBJ_bsearch_ex_ are generic functions that don't
really belong with the OBJ API, but should rather be generic utility
functions.  The ending underscore indicates that they are considered
internal, even though they are declared publicly.

Since crypto/stack/stack.c uses OBJ_bsearch_ex_, the stack API ends up
depending on the OBJ API, which is unnecessary, and carries along
other dependencies.

Therefor, a generic internal function is created, ossl_bsearch().
This removes the unecessary dependencies.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8899)