RISC-V: Add required tls to read thread pointer test
The read-thread-pointer test may require the gcc configured
with --enable-tls. If no, there x4 (aka tp) register will not
be presented in the assembly code.
This patch requires the tls for the dg checking. It will perform
the test checking if --enable-tls and mark the test as unsupported
if --disable-tls.
Configured with --enable-tls:
=== gcc Summary ===
of expected passes 16
Configured with --disable-tls:
=== gcc Summary ===
of unsupported tests 8