Exclude examples/qmasm-maze from source distributions

qmasm-maze is a binary executable produced from qmasm-maze.go.
Because it runs only on Linux + Intel64, it is best not to include
qmasm-maze in a source distribution.  Rather, users should compile it
from source.

Author: spakin

MANIFEST.in

@@ -1,4 +1,5 @@
 include README.md
 include LICENSE.md
-recursive-include examples *
 recursive-include extras *
+recursive-include examples *
+exclude examples/qmasm-maze