[roll] Roll fuchsia [rbe] auto start/stop reproxy around any command

This can be used to test RBE, while having tool commands
use a simplified wrapper that doesn't repeatedly start and stop the
reproxy.

usage:
  [modify build/toolchain/clang_toolchain.gni: ]

  build/rbe/fuchsia-reproxy-wrap.sh -- fx build

Eventually, this will be integrated into fx itself.

Tested:
 ./build/rbe/fuchsia-reproxy-wrap.sh -- sleep 15s &
 kill -{INT,HUP,TERM} [pid]

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/542684
Original-Revision: cba85836652512444f185859e27c6dde33789e61
GitOrigin-RevId: 785bb6efaac2c8e2ef202e53f10d8ee6c262abff
Change-Id: I644c2c51530b7a4570ef5eaf455710f15b92ca6b
diff --git a/stem b/stem
index e1b0ae7..03d0e74 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
              githooks=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="85d1b82207aa12dcaea8f9aa322d0a1824bf4fc0"/>
+             revision="cba85836652512444f185859e27c6dde33789e61"/>
   </projects>
   <hooks>
     <hook name="install-environment"