[Fix] Accidently changed the type of a libgomp argument in r219003.

  Only subsequent patches introduced tests for the signature in the
  generated IR, thus the tests were wrong too and are adjusted now.



git-svn-id: https://llvm.org/svn/llvm-project/polly/trunk@219017 91177308-0d34-0410-b5e6-96231b3b80d8