Enable -Wsign-compare for netd and fix warnings

Test: atest netd_unit_test netd_integration_test resolv_integration_test
Change-Id: I84347de8f3a3ec0dcc8979037b9c265d145a35f7
diff --git a/Android.bp b/Android.bp
index 64831b8..32e719b 100644
--- a/Android.bp
+++ b/Android.bp
@@ -11,9 +11,9 @@
         // Override -Wno-error=implicit-fallthrough from soong
         "-Werror=implicit-fallthrough",
         "-Wnullable-to-nonnull-conversion",
+        "-Wsign-compare",
         "-Wthread-safety",
         "-Wunused-parameter",
-        "-Wsign-compare",
     ],
     tidy: true,
     tidy_checks: [