android: Re-enable thinlto in official builds.

ToTAndroidOfficial is green after https://chromium-review.googlesource.com/1257202
so chances are this is fixed in the recent clang roll.

Bug: 887272,889062
Change-Id: Iea7a64507cea2cc0410f851af68a5f9fc008b5ae
Reviewed-on: https://chromium-review.googlesource.com/c/1258287
Commit-Queue: Egor Pasko <pasko@chromium.org>
Reviewed-by: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596159}

build/config/compiler/compiler.gni

@@ -52,8 +52,7 @@ declare_args() {
   # Enables support for ThinLTO, which links 3x-10x faster than full LTO. See
   # also http://blog.llvm.org/2016/06/thinlto-scalable-and-incremental-lto.html
   # TODO(https://crbug.com/887272): Reenable on is_android && is_official_build
-  use_thin_lto =
-      is_cfi || (is_android && is_official_build && llvm_force_head_revision)
+  use_thin_lto = is_cfi || (is_android && is_official_build)
 
   # Tell VS to create a PDB that references information in .obj files rather
   # than copying it all. This should improve linker performance. mspdbcmf.exe