sys-libs/glibc: add USE=static-pie to install rcrt1.o

sys-libs/glibc: add USE=static-pie to install rcrt1.o

To add support for gcc's -static-pie flag glibc needs
to provide a few runtile files like rcrt1.o. Let's install
those when requested.

Noticed when looked at static-pie failures in bug #712356.
The change should not fix test failures, but will provide
a way to easily sanity-check static-pie health with minimal
test.

Bug: https://bugs.gentoo.org/712356
Package-Manager: Portage-2.3.93, Repoman-2.3.20
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>