Enable clang-tidy for clatd.

Enable the same warnings used elsewhere in the tree, and fix two
warnings it found (a safe use of strcpy, and a missing O_CLOEXEC
when opening the tun device node.

Test: builds, boots, clatd works
Test: m clatd clatd_test clatd_microbenchmark && atest clatd_test
Change-Id: I9a5ea4de5f31d3c495871250a6493b07535a604b
diff --git a/Android.bp b/Android.bp
index e0eeb2e..98b4010 100644
--- a/Android.bp
+++ b/Android.bp
@@ -54,6 +54,20 @@
         "liblog",
         "libnetutils",
     ],
+
+    // Only enable clang-tidy for the daemon, not the tests, because enabling it for the
+    // tests substantially increases build/compile cycle times and doesn't really provide a
+    // security benefit.
+    tidy: true,
+    tidy_checks: [
+        "-*",
+        "cert-*",
+        "clang-analyzer-security*",
+        "android-*",
+    ],
+    tidy_flags: [
+        "-warnings-as-errors=clang-analyzer-security*,cert-*,android-*",
+    ],
 }
 
 // The configuration file.