Adding benchmarks

diff --git a/src/Benchmarks/sudoku-csolver b/src/Benchmarks/sudoku-csolver
new file mode 160000 (submodule)
index 0000000..4a22c3f
--- /dev/null
+++ b/src/Benchmarks/sudoku-csolver
@@ -0,0 +1 @@
+Subproject commit 4a22c3f08f52ac957792d389d0518455aab3e9a1