[clang] Thread-local variables are not supported
clang require @tls_get_addr@ to be implemented on low level (libc) to support @thread@ variables. Bionic doesn't provide it. GCC workaround it by using emulated TLS feature in libgcc. Clang don't support it yet, but "here":https://llvm.org/bugs/show_bug.cgi?id=23566 is corresponding ticket, with patches suggested.