Re-add forced cachedir creation.

In CL:33875, we added caching; that caching specifically forced
the cache dir to be created before trying any upgrades... that
code was -1'd out however.

Turns out, it was needed; if this is the first run and no cache-dir
exists, but an upgrade is necessary, it would fail.

BUG=chromium-os:34450
TEST=manual, harass vapier to test it in addition.

Change-Id: I44ff2c80f832b8e72a48f4131f1d5cfe7c1e3b1b
Reviewed-on: https://gerrit.chromium.org/gerrit/34331
Reviewed-by: Brian Harring <ferringb@chromium.org>
Tested-by: Brian Harring <ferringb@chromium.org>
diff --git a/scripts/cros_sdk.py b/scripts/cros_sdk.py
index 6ea6db4..8976014 100644
--- a/scripts/cros_sdk.py
+++ b/scripts/cros_sdk.py
@@ -355,6 +355,7 @@
 
         sdk_cache = os.path.join(options.cache_dir, 'sdks')
         distfiles_cache = os.path.join(options.cache_dir, 'distfiles')
+        osutils.SafeMakedirs(options.cache_dir)
 
         for target in (sdk_cache, distfiles_cache):
           src = os.path.join(SRC_ROOT, os.path.basename(target))