libui: remove frameworks/native/include/ui symlink

Remove the global include for ui. Only symlink the two
headers that are depended on by vendor code.

The changes to Region and RegionHelepr were made by the
linter. No code was changed.

Bug: 145624276
Test: Compiles

Change-Id: I1bbd99581faa703f73329ebde2da05d55950f910
13 files changed