Enable clang-tidy for libsysutils.

Enable the same warnings used elsewhere in the tree, and fix the
two warnings it found (two safe uses of strcpy and one use of
atoi).

Test: builds, boots
Test: atest libsysutils_tests
Test: atest --test-mapping system/netd
Change-Id: I8e5d04da20cc4127439ad9fbda0e4e64f0e671d3
diff --git a/libsysutils/Android.bp b/libsysutils/Android.bp
index da5d86c..ccda5d1 100644
--- a/libsysutils/Android.bp
+++ b/libsysutils/Android.bp
@@ -26,6 +26,19 @@
     ],
 
     export_include_dirs: ["include"],
+
+    tidy: true,
+    tidy_checks: [
+        "-*",
+        "cert-*",
+        "clang-analyzer-security*",
+        "android-*",
+    ],
+    tidy_checks_as_errors: [
+        "cert-*",
+        "clang-analyzer-security*",
+        "android-*",
+    ],
 }
 
 cc_test {