[OPENMP] -fopenmp enables OpenMP support (fix for http://llvm.org/PR23492)

-fopenmp turns on OpenMP support and links libiomp5 as OpenMP library. Also there is -fopenmp={libiomp5|libgomp} option that allows to override effect of -fopenmp and link libgomp library (if -fopenmp=libgomp is specified).
Differential Revision: http://reviews.llvm.org/D9736

llvm-svn: 237769

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1643,12 +1643,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
     Opts.setMSPointerToMemberRepresentationMethod(InheritanceModel);
   }
 
-  // Check if -fopenmp= is specified.
-  if (const Arg *A = Args.getLastArg(options::OPT_fopenmp_EQ)) {
-    Opts.OpenMP = llvm::StringSwitch<bool>(A->getValue())
-        .Case("libiomp5", true)
-        .Default(false);
-  }
+  // Check if -fopenmp is specified.
+  Opts.OpenMP = Args.hasArg(options::OPT_fopenmp);
 
   // Record whether the __DEPRECATED define was requested.
   Opts.Deprecated = Args.hasFlag(OPT_fdeprecated_macro,