manifest_fixer: Set targetSdkVersion to '16' for libraries

manifest_fixer.py sets a lib's targetSdkVersion to '15' if it is
not explicitly set.  But ManifestMerger will add dangerous
permissions CALL_LOG_READ/CALL_LOG_WRITE if the following
conditions are met:

    - The app's targetSdkVersion is >16
    - A linked lib's targetSdkVersion is <16
    - The app has CONTACTS_READ/CONTACTS_WRITE permissions

This condition is triggered for some (OEM) app builds (of
Settings).  Update manifest_fixer.py to use '16' as its default
targetSdkVersion so that manifest_merge doesn't add these
dangerous permissions.

Change-Id: Id5f41f7da98c190c8d145fceba0085cf473f4c7a
diff --git a/scripts/manifest_fixer.py b/scripts/manifest_fixer.py
index c59732b..55d0fd1 100755
--- a/scripts/manifest_fixer.py
+++ b/scripts/manifest_fixer.py
@@ -121,7 +121,7 @@
       # is empty.  Set it to something low so that it will be overriden by the
       # main manifest, but high enough that it doesn't cause implicit
       # permissions grants.
-      target_attr.value = '15'
+      target_attr.value = '16'
     else:
       target_attr.value = target_sdk_version
     element.setAttributeNode(target_attr)