[roll] Roll fuchsia [superproject] Roll llvm-project/libc 6a56381..851ec34 (3 commits)

851ec34 [libc] Add basic utility support for timing functions on the GPU
b6a3e34 [libc][Obvious] Use the current binary dir instead of the base one
cdedf50 [libc] Fix installing GPU headers

GitOrigin-RevId: fbad8310f501e045ce5c1992f5450bba2a24dbf5
Roller-URL: https://ci.chromium.org/b/8777456645577881841
CQ-Do-Not-Cancel-Tryjobs: true
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/876017
Original-Revision: d23fdb3346ac3be4a11d93a02dfd1b822b7f4f08
Change-Id: Ib6ea8383003bdbc9676f6c872d6a15b872aace99
diff --git a/stem b/stem
index 0d4ab1c..435c9c4 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="0295ea34f71b1c1cab0891948e8703ed90a21345"/>
+             revision="d23fdb3346ac3be4a11d93a02dfd1b822b7f4f08"/>
   </projects>
   <hooks>
     <hook name="install-environment"