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)

 This is NOT the official version of dialog.  This version has been

 significantly modified from the original.  It is for use by the Linux

 kernel configuration script.  Please do not bother Savio Lam with 

 questions about this program.