OpenLibm uses the __weak_reference() macro for platforms where double
and long double use the same layout. That way functions only need to be
provided by the library once. The point is, in this specific case we
want to use strong references; not weak references.
Strong references can be used to give a symbol a second name. If you
look at the resulting object file, you will have two symbols with the
same offset and size. Weak references are different, in the sense that
they are marked in such a way that they act as fallbacks. They are only
used if an explicitly matching symbol is missing.
Put external headers before internal ones. While there, replace a lot of
occurences of "openlibm.h" with <openlibm.h>. It should be thought of as
an external header, as it is installed along with the library.
