[OPENMP]Set default version to OpenMP 4.5.

Since clang fully supports OpenMP 4.5, set the default version to 4.5
instead of 3.1.

llvm-svn: 368172
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index d1e9b14..9bd6023 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2894,8 +2894,8 @@
     }
   }
 
-  // Check if -fopenmp is specified.
-  Opts.OpenMP = Args.hasArg(options::OPT_fopenmp) ? 1 : 0;
+  // Check if -fopenmp is specified and set default version to 4.5.
+  Opts.OpenMP = Args.hasArg(options::OPT_fopenmp) ? 45 : 0;
   // Check if -fopenmp-simd is specified.
   bool IsSimdSpecified =
       Args.hasFlag(options::OPT_fopenmp_simd, options::OPT_fno_openmp_simd,