cros_setup_toolchains: generate prebuilts for rust-bootstrap 1.49.0

...mostly so we can pull these down and cache them, so upgrading to rust
1.50 is doable.

BUG=chromium:1185882
TEST=sdk tryjob

Change-Id: Ia8f6f8c199d406ec1ac1523b7707c5380596f169
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2774614
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
diff --git a/scripts/cros_setup_toolchains.py b/scripts/cros_setup_toolchains.py
index 51932c9..948ab06 100644
--- a/scripts/cros_setup_toolchains.py
+++ b/scripts/cros_setup_toolchains.py
@@ -74,7 +74,7 @@
 HOST_POST_CROSS_PACKAGES = (
     'dev-lang/rust',
     'dev-lang/rust-bootstrap:0',
-    'dev-lang/rust-bootstrap:1.48.0',
+    'dev-lang/rust-bootstrap:1.49.0',
     'virtual/target-sdk-post-cross',
     'dev-embedded/coreboot-sdk',
 )
@@ -84,7 +84,7 @@
 # so we have to list them here and wait.  Once it completes, entries here can
 # be removed so they'll end up on bots & dev's systems.
 NEW_PACKAGES = (
-    'dev-lang/rust-bootstrap:1.48.0',
+    'dev-lang/rust-bootstrap:1.49.0',
 )
 
 # Enable the Go compiler for these targets.