toolchain: add hidden symbol for PIE support

uClibc-ng does not support PIE for some architectures as
arc and m68k. It isn't implemented in the static linking case, too.
With musl toolchains you might have static PIE support with little
patching of gcc. Static linking for GNU libc isn't enabled in
buildroot. Fixup any package using special treatment of PIE.
(grep -ir pie package/*/*.mk)

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
[Thomas: use positive logic.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>