Add a test app for thread local variables with destructors

Dockerfile.dev

@@ -60,9 +60,10 @@ RUN ./build-libcxx.sh $TOOLCHAIN_PREFIX
 COPY test/*.cpp ./test/
 RUN cd test && \
     for arch in $TOOLCHAIN_ARCHS; do \
-        for test in hello-cpp hello-exception; do \
+        for test in hello-cpp hello-exception tlstest-main; do \
             $arch-w64-mingw32-clang++ $test.cpp -o $test-$arch.exe || exit 1; \
         done; \
+        $arch-w64-mingw32-clang++ tlstest-lib.cpp -shared -o tlstest-lib-$arch.dll || exit 1; \
     done
 
 # Build libssp