[OPENMP5.0]Add support for device_type clause in declare target
construct.

OpenMP 5.0 introduced new clause for declare target directive, device_type clause, which may accept values host, nohost, and any. Host means
that the function must be emitted only for the host, nohost - only for
the device, and any - for both, device and the host.

llvm-svn: 369775
diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index 2ca7ebc..473c6f7 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -4021,6 +4021,7 @@
   case OMPC_reverse_offload:
   case OMPC_dynamic_allocators:
   case OMPC_atomic_default_mem_order:
+  case OMPC_device_type:
     llvm_unreachable("Clause is not allowed in 'omp atomic'.");
   }
 }