p2000: add new commands

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>

Author: derrickstolee

t/perf/p2000-sparse-operations.sh

@@ -123,5 +123,6 @@ test_perf_on_all git blame $SPARSE_CONE/f3/a
 test_perf_on_all git read-tree -mu HEAD
 test_perf_on_all git checkout-index -f --all
 test_perf_on_all git update-index --add --remove $SPARSE_CONE/a
+test_perf_on_all git sparse-checkout reapply
 
 test_done