run-tests: Stop explicitly linking against -lssp for the fortification test

Since libmingwex.a provides these routines now, we don't need to
specify -lssp manually.

Dockerfile.dev

@@ -164,7 +164,7 @@ RUN cd test && \
             $arch-w64-mingw32-clang $test.c -o $arch/$test.exe -fstack-protector-strong || exit 1; \
         done; \
         for test in bufferoverflow; do \
-            $arch-w64-mingw32-clang $test.c -o $arch/$test.exe -lssp -D_FORTIFY_SOURCE=2 -O2 || exit 1; \
+            $arch-w64-mingw32-clang $test.c -o $arch/$test.exe -D_FORTIFY_SOURCE=2 -O2 || exit 1; \
         done; \
     done