Merging r198863:

------------------------------------------------------------------------
r198863 | stpworld | 2014-01-09 07:26:12 -0500 (Thu, 09 Jan 2014) | 6 lines

Fixed old typo in ScalarEvolution, that caused wrong SCEVs zext operation.
Detailed description is here:
http://llvm.org/bugs/show_bug.cgi?id=18000#c16

For participation in bugfix process special thanks to David Wiberg.

------------------------------------------------------------------------

llvm-svn: 205794