Commit a test for match-full-lines.

I unfortunately neglected to add it in r260540, but it has been
sitting in my working dir ever since. D'oh.

Modified to work with r290069, which made the CHECK patterns
themselves whitespace-sensitive as well, and remove the test added
then, as this tests both strict and non-strict modes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291499 91177308-0d34-0410-b5e6-96231b3b80d8