Build with -cros-debug by default.

We need to make sure that we are building without asserts.

BUG=None
TEST=local build succeeded.

Change-Id: Ifdac90c6c3f8fb3fc027cb1d8e3cfbeec21ba398
Reviewed-on: https://chromium-review.googlesource.com/537996
Commit-Ready: Luis Lozano <llozano@chromium.org>
Tested-by: Luis Lozano <llozano@chromium.org>
Reviewed-by: Ting-Yuan Huang <laszio@chromium.org>
diff --git a/build_chromeos.py b/build_chromeos.py
index 6b4f4dc..0b0676d 100755
--- a/build_chromeos.py
+++ b/build_chromeos.py
@@ -142,7 +142,7 @@
   # Build with afdo_use by default.
   # To change the default use --env="USE=-afdo_use".
   build_packages_env = misc.MergeEnvStringWithDict(
-      build_packages_env, {'USE': 'chrome_internal afdo_use'})
+      build_packages_env, {'USE': 'chrome_internal afdo_use -cros-debug'})
 
   build_packages_command = misc.GetBuildPackagesCommand(
       board=options.board, usepkg=options.vanilla_image, debug=options.debug)