[test] Convert test for PR36720 to c89
[test] Convert test for PR36720 to c89

GCC 4.8.5 defaults to this old C standard. I think we should make the
tests pass a newer -std=c99|c11 but that's too intrusive for now...

Differential Revision: https://reviews.llvm.org/D50084

git-svn-id: f99161ee8ccfe2101cbe1bdda2220bce2ed25485@338490 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/openmp,llvm-mirror/openmp,llvm-mirror/openmp,llvm-mirror/openmp,llvm-mirror/openmp