Set proper sdk_version

This android_library used too broader sdk_version even though there is
no hidden API usage.

Bug: 143736861
Test: m nothing
Change-Id: Iacd3e77587d5dc25edbf5ac64c7eb726cb7dba55
diff --git a/Android.bp b/Android.bp
index 9927416..776755b 100644
--- a/Android.bp
+++ b/Android.bp
@@ -36,4 +36,5 @@
         "strings/res",
     ],
     min_sdk_version: "14",
+    sdk_version: "current"
 }