Update code listings in LLVM tutorial.

Several LLVM headers are moved.  The code listings in
LLVM tutorial are not updated yet.

This CL removes the code replica in the .rst, and replace
them with a literalinclude directive, so that sphinx can
include the latest code automatically.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183607 91177308-0d34-0410-b5e6-96231b3b80d8