A number of users have hit problems with the musl-gcc wrapper and
underlying gccs built for default-pie, due to the specfile assuming
non-pie is the default. The attached patch should fix that by using
the pic-compatible versions of the crt files regardless of whether the
output is pie or not. There's really no reason for the
non-pic-compatible files to ever be used except saving (likely a
single-digit number of) bytes of text.

For static-pie, where a special rcrt1.o file is needed in place of the
normal crt1, this will not work, but as far as I know all deployed gcc
toolchains with default-pie do not honor the default-pie with -static
and don't even support -static -pie (only -static-pie if anything)
since glibc didn't support it until very recently. We could probably
make -static-pie (and maybe -static -pie?) work with musl-gcc on such
toolchains if we wanted as a separate patch, but right now I just want
to fix the defaults that are breaking things for users..

Let me know if there's anything wrong with this or if it doesn't fix
the problem.

Rich