Remove ; from closing namespaces in libs/hwui

When closing a namespace a } is sufficient. It doesn't need to be };
like closing a class or enum.

Within frameworks/base/libs/hwui there is a mix between } and }; when
closing a namespace. There are even mixes between a .h and the
corresponding .cpp files.

In a separate CL I was asked to not close with };. That was a good
comment. I adopted the style from nearby code. This CL cleans up the
nearby code.

Test: I made sure the code still built as expected.
Change-Id: Ieb314a4f48d6e33752463f3be4361fdc9be97482