[PATCH] ld: improve shared tests for AIX

[CHIGOT, CLEMENT]

> It's now possible to refer symbols in the main program from the
> shared library. However, it still impossible to have the same
> overriden features between shared objects and mains than ELF,
> without using the runtime linking feature which isn't yet fully
> available.
>
> ld/ChangeLog:
>
>         * testsuite/ld-shared/shared.exp: Improve XCOFF support
>         * testsuite/ld-shared/main.c: Likewise.
>         * testsuite/ld-shared/sh1.c: Likewise.
>         * testsuite/ld-shared/xcoff.dat: Likewise.

Gentle ping,

Thanks,
Clément