selftests: kvm: fix for compilers that do not support -no-pie

-no-pie was added to GCC at the same time as their configuration option
--enable-default-pie.  Compilers that were built before do not have
-no-pie, but they also do not need it.  Detect the option at build
time.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>