Skia bots: use deps_os = 'all'

scripts/slave/recipes/skia/skia.expected/failed_dm.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE[depot_tools]/gclient.py",
       "config",
       "--spec",
-      "cache_dir = None\nsolutions = [{'deps_file': 'DEPS', 'managed': True, 'name': 'skia', 'url': 'https://skia.googlesource.com/skia.git'}]"
+      "cache_dir = None\ndeps_os = {'skia': 'all'}\nsolutions = [{'deps_file': 'DEPS', 'managed': True, 'name': 'skia', 'url': 'https://skia.googlesource.com/skia.git'}]"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PATH": "%(PATH)s:RECIPE_PACKAGE[depot_tools]"
     },
     "name": "gclient setup"
   },
   {
     "cmd": [
       "python",
@@ skipping 369 matching lines @@
       "SKIA_OUT": "[SLAVE_BUILD]/skia/out/Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug"
     },
     "name": "nanobench"
   },
   {
     "name": "$result",
     "reason": "Failed build steps: dm",
     "status_code": 1
   }
 ]