Don't call uninitialized sandbox helper function from blacklist intercepts.

When mapping a section into a different process, the IsSameProcess
function would crash invoking an uninitialized nt export.

BUG=330178
TEST=NONE

Review URL: https://codereview.chromium.org/93513011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242272 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242272