Rename "polly-test" in the document and script.

The Makefile rule "polly-test" has been renamed to
"check-polly" in r182171.  This CL updates the document and
the automatic build script.


git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@188624 91177308-0d34-0410-b5e6-96231b3b80d8