Auto merge of #123257 - ChrisDenton:enable-tls, r=fmease

Re-enable `has_thread_local` for i686-msvc

A few years back, `has_thread_local` was disabled as a workaround for a compiler issue. While the exact cause was never tracked down, it was suspected to be caused by the compiler inlining a thread local access across a dylib boundary. This should be fixed now so let's try again.

Author: bors