[NaCl SDK] move VSNaClSDKRoot into ConfigurationGeneral section

This change removes a lot of the hacking we were previously
doing to make sure that the value of VSNaClSDKRoot was
available in all the right place.

BUG=

Review URL: https://codereview.chromium.org/11225037

git-svn-id: https://nativeclient-sdk.googlecode.com/svn/trunk/src@1457 050acbb0-2703-11df-ab0a-9f3f633ae91d
6 files changed