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

scripts/manifest_fixer.py

@@ -121,7 +121,7 @@ def raise_min_sdk_version(doc, min_sdk_version, target_sdk_version, library):
       # 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)

scripts/manifest_fixer_test.py

@@ -173,7 +173,7 @@ class RaiseMinSdkVersionTest(unittest.TestCase):
     """Tests inserting targetSdkVersion when minSdkVersion exists."""
 
     manifest_input = self.manifest_tmpl % self.uses_sdk(min='27')
-    expected = self.manifest_tmpl % self.uses_sdk(min='28', target='15')
+    expected = self.manifest_tmpl % self.uses_sdk(min='28', target='16')
     output = self.raise_min_sdk_version_test(manifest_input, '28', '29', True)
     self.assertEqual(output, expected)
 
@@ -189,7 +189,7 @@ class RaiseMinSdkVersionTest(unittest.TestCase):
     """Tests inserting targetSdkVersion when minSdkVersion does not exist."""
 
     manifest_input = self.manifest_tmpl % ''
-    expected = self.manifest_tmpl % self.uses_sdk(min='28', target='15')
+    expected = self.manifest_tmpl % self.uses_sdk(min='28', target='16')
     output = self.raise_min_sdk_version_test(manifest_input, '28', '29', True)
     self.assertEqual(output, expected)