Only use the Darwin linker's -export_dynamic option with supported versions.

Related to <rdar://problem/14578094>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187680 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 33e2803..dfaffaa 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -4517,6 +4517,9 @@
       CmdArgs.push_back("-demangle");
   }
 
+  if (Args.hasArg(options::OPT_rdynamic) && Version[0] >= 137)
+    CmdArgs.push_back("-export_dynamic");
+
   // If we are using LTO, then automatically create a temporary file path for
   // the linker to use, so that it's lifetime will extend past a possible
   // dsymutil step.
@@ -4724,9 +4727,6 @@
   if (Args.hasArg(options::OPT_ObjC) || Args.hasArg(options::OPT_ObjCXX))
     CmdArgs.push_back("-ObjC");
 
-  if (Args.hasArg(options::OPT_rdynamic))
-    CmdArgs.push_back("-export_dynamic");
-
   CmdArgs.push_back("-o");
   CmdArgs.push_back(Output.getFilename());