Add a flag to convert only a subset of partitions to COW

Test: th
Change-Id: I2e9be56083b3c4d7f733e94059d372c14d136c31
diff --git a/Android.bp b/Android.bp
index 72b9f73..7049acd 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1126,6 +1126,7 @@
         "libbase",
         "libcow_operation_convert",
         "libcow_size_estimator",
+        "libgflags",
         "libpayload_consumer",
         "libpayload_extent_ranges",
         "libpayload_extent_utils",