Make sandbox target a settings target type to fix a linker error.

BUG=92164
TEST=Clobber build compiles, trybots

Review URL: http://codereview.chromium.org/7602016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@96425 0039d316-1c4b-4281-b951-d872f2087c98

sandbox/sandbox.gyp

@@ -136,7 +136,7 @@
       'targets': [
         {
           'target_name': 'sandbox',
-          'type': 'static_library',
+          'type': 'settings',
           'conditions': [
             # Only compile in the seccomp code for the flag combination
             # where we support it.