Fix elf/tst-tls9-static build

This patch fixes the tst-tlsmod[5/6].so build in system that uses
-Wl,--as-needed as default in linker option.  Without this option
the testing shared library that does not have libc.so in DT_NEEDED
and the tst-tls9-static fails in architecture that use the
./sysdeps/unix/sysv/linux/<arch>/dl-static.c trick.