s390x: Fix static PIE condition for toolchain bootstrapping.

The static PIE configure check uses link tests.  When bootstrapping
a cross-toolchain, the link tests fail due to missing crt-files /
libc.so.  As we explicitely want to test an issue in binutils (ld),
we now also explicitely check for known linker versions.

See also commit 368b7c61
S390: Use compile-only instead of also link-tests in configure.