init: only use signed-integer-overflow sanitizer

We've blown up twice in init due to the unsigned integer overflow
sanitizer despite the overflows in question being both defined and
intentional.

Test: boot
Change-Id: I08effe3202ac1367d858982ff5478b3a088bab37
diff --git a/init/Android.bp b/init/Android.bp
index 8294598..aaef7e9 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -18,7 +18,7 @@
     name: "init_defaults",
     cpp_std: "experimental",
     sanitize: {
-        misc_undefined: ["integer"],
+        misc_undefined: ["signed-integer-overflow"],
     },
     cppflags: [
         "-DLOG_UEVENTS=0",