[prebuilt] Roll Clang toolchain

Change-Id: I7fbc5bbf10c02d3957da7f84e2ff704324e1253a
diff --git a/prebuilt/zircon.ensure b/prebuilt/zircon.ensure
index 6079558..b8eeed5 100644
--- a/prebuilt/zircon.ensure
+++ b/prebuilt/zircon.ensure
@@ -30,7 +30,7 @@
 
 # Clang
 @Subdir clang
-fuchsia/clang/${platform} git_revision:4c6142e3bc986b79dc0f7c9deafc82af13eab12f
+fuchsia/clang/${platform} git_revision:4ad2908c9b4b485a0bf683f62a68e22f040b9f61
 
 # GCC
 @Subdir gcc
diff --git a/prebuilt/zircon.versions b/prebuilt/zircon.versions
index 43006ed..45be036 100644
--- a/prebuilt/zircon.versions
+++ b/prebuilt/zircon.versions
@@ -1,8 +1,8 @@
 # This file is generated by scripts/update-prebuilt-versions.  DO NOT EDIT!
 # Instead, edit zircon.ensure and run the script.
 
-clang/linux-amd64 2d85f1f7e2f347dc8374b5379ddf8cfb41391808
-clang/mac-amd64 e6b5984e41e86be0c73927003b5e29b403c49219
+clang/linux-amd64 bce995173b8748b2728c8f97f36ad1667c1b21e0
+clang/mac-amd64 4397cd6c90682fe7235b72ede946d79757e659c4
 gcc/linux-amd64 d1d9edff39e1c206b8d5050116724c10228f6e08
 gcc/mac-amd64 5fbe47110c48b47ccd802b5e4e2686dd5a51432c
 sysroot/linux-amd64 ae0677829357edb199c21e76b1ea31eb8ef62817