libutils: Limit integer sanitize to target only

This matches what the Android.mk defined, and should temporarily fix
builds that were broken with:

system/core/libutils/Unicode.cpp:225:12: runtime error: unsigned integer
overflow: 0 - 1 cannot be represented in type 'size_t' (aka 'unsigned
long')

Change-Id: I0363b42fc2d62dfd2d05649c9aa9ef0be573e20a
diff --git a/libutils/Android.bp b/libutils/Android.bp
index 3451bbd..1038db4 100644
--- a/libutils/Android.bp
+++ b/libutils/Android.bp
@@ -66,6 +66,10 @@
                 "libdl",
                 "liblog",
             ],
+
+            sanitize: {
+                misc_undefined: ["integer"],
+            },
         },
 
         host: {
@@ -96,9 +100,6 @@
     },
 
     clang: true,
-    sanitize: {
-        misc_undefined: ["integer"],
-    },
 }
 
 // Include subdirectory makefiles