VS10: Refactor link options collection

Avoid collecting the link options twice.  Collect them once in a
LinkOptions member and use it from both places.  We already do this for
compiler options with the ClOptions member.
diff --git a/Source/cmIDEOptions.cxx b/Source/cmIDEOptions.cxx
index d9c0e87..76a60cf 100644
--- a/Source/cmIDEOptions.cxx
+++ b/Source/cmIDEOptions.cxx
@@ -177,3 +177,14 @@
 {
   this->FlagMap.erase(flag);
 }
+
+//----------------------------------------------------------------------------
+const char* cmIDEOptions::GetFlag(const char* flag)
+{
+  std::map<cmStdString, cmStdString>::iterator i = this->FlagMap.find(flag);
+  if(i != this->FlagMap.end())
+    {
+    return i->second.c_str();
+    }
+  return 0;
+}