test-many-klibc: Always use GNU ld for riscv64, s390x, and sparc64

* LLD 13 doesn't implement linker relaxation for RISC-V, which makes
  it fairly useless.  Having made relaxation work, I don't want to go
  back and make it conditional.
* LLD 13 doesn't seem to handle SPARC-specific relocations yet.
* Debian's build of LLD 13 doesn't seem to include IBM Z (s390x)

So introduce a "mixed" toolchain of Clang + GNU ld, and test that
instead of pure LLVM for these architectures.
1 file changed
tree: 851630ba57db0056628e3ef5da6c4633ea8153ba
  1. .gitignore
  2. newklibc
  3. test-many-klibcs