Revert "[X86] Revert -fno-plt __tls_get_addr workaround for old GNU ld"

This reverts commit 2679e8bb.

This change is a significant backwards-compatibility break, which
does in fact break the entire Rust ecosystem, which uses an
-fno-plt -mrelax-relocations=0 default.

Please go through pre-commit review for this change in order to
gain broader consensus.