Opened https://bugs.llvm.org/show_bug.cgi?id=33528 for build issue with new project LLVMTestingSupport. Disabled it in the build for now.

Opened  https://crbug.com/735506  for LLVMTestingSupport breakage. Upgrade done otherwise.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/316231a7ad8b31566edabcb1ed3ac5761185bbc0

commit 316231a7ad8b31566edabcb1ed3ac5761185bbc0
Author: Manoj Gupta <manojgupta@google.com>
Date: Mon Jun 26 21:08:43 2017

LLVM: Drop patches where upstream bugs have been fixed.

Drop 3 patches where the upstream bug has been fixed
related to gtest, Sphinx and LLVMTestingSupport.
Fixes the bug related to LLVMTestingSupport installation.

BUG= chromium:735105 
TEST=LLVM builds with and wihout USE="llvm-next"

Change-Id: I77113c1f615004898c35da6a32b79ac33da54dfc
Reviewed-on: https://chromium-review.googlesource.com/549002
Commit-Queue: Manoj Gupta <manojgupta@chromium.org>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Trybot-Ready: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Yunlian Jiang <yunlian@chromium.org>

[delete] https://crrev.com/f6b9da621c122c0b852862b052574dab194619e1/sys-devel/llvm/files/cmake/0004-cmake-Do-not-install-libgtest.patch
[delete] https://crrev.com/f6b9da621c122c0b852862b052574dab194619e1/sys-devel/llvm/files/cmake/0003-cmake-Add-an-ordering-dep-between-HTML-man-Sphinx-ta.patch
[rename] https://crrev.com/316231a7ad8b31566edabcb1ed3ac5761185bbc0/sys-devel/llvm/llvm-5.0_pre300080-r12.ebuild
[delete] https://crrev.com/f6b9da621c122c0b852862b052574dab194619e1/sys-devel/llvm/files/llvm-next-disable-testing-support.patch