Fix issue with zero-size duplicate function symbols.

Summary:
While working on PLT dyno stats I've noticed that we were missing
BinaryFunctions for some symbols that were not PLT. Upon closer inspection
turned out that those symbols were marked as zero-sized functions in
symbol table, but they had duplicates with non-zero size. Since the
zero-size symbols were preceding other duplicates, we were not creating
BinaryFunction for them and they were not added as duplicates.

The 2 most prominent functions that were missing for a test were free() and
malloc().  There's not much to optimize in these functions, but they were
contributing quite significantly to dyno stats.

As a result dyno stats for this test needed an adjustment.

Also several assembly functions (e.g. _init()) had zero size, and now we
set the size to the max size and start processing those. It's good for
coverage but will not affect the performance.

(cherry picked from FBD3874622)