Drop -rdynamic from deleted-lib.so link step

Drop -rdynamic from deleted-lib.so link step

-rdynamic is meant for ELF objects that need to export internal
symbols to libraries they link to, but deleted-lib.so does not link to
anything else and doesn't have any internal symbols.

Note that the "deleted" test program does link to deleted-lib.so, but
deleted-lib.so being a shared object, will automatically export the
(non-hidden) "libfunc" symbol anyway.

Signed-off-by: Ulf Hermann <ulf.hermann@qt.io>