OpenMP version 5.0 added

Add build option LIBOMP_OMP_VERSION=50, 5.0 headers, and add the year/month
associated with OpenMP 5.0 in relevant source locations. Also, remove the
deprecated LIBOMP_OMP_VERSION=41 option.

Patch by Olga Malysheva

Differential Revision: https://reviews.llvm.org/D30450

llvm-svn: 297083
diff --git a/openmp/runtime/src/kmp_version.cpp b/openmp/runtime/src/kmp_version.cpp
index 8b782b3..6e68baf 100644
--- a/openmp/runtime/src/kmp_version.cpp
+++ b/openmp/runtime/src/kmp_version.cpp
@@ -89,7 +89,9 @@
 int const __kmp_version_minor = KMP_VERSION_MINOR;
 int const __kmp_version_build = KMP_VERSION_BUILD;
 int const __kmp_openmp_version =
-    #if OMP_45_ENABLED
+    #if OMP_50_ENABLED
+        201611;
+    #elif OMP_45_ENABLED
         201511;
     #elif OMP_40_ENABLED
         201307;