complibs/libelf: build with -fPIC

libelf is used by gcc to build the lto-plugin used
by binutils' gold to perform LTO.

This requires that files in libelf be compiled with
-fPIC to generate a proper .so.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from c48aba92cbeb7b7dce956a63ec65d3296735cc16)

 reporter_name="Alexander BIGGA"

 reporter_url="http://sourceware.org/ml/crossgcc/2008-07/msg00000.html"

 reporter_comment=""