COMP: Fix shadowed local variable warning.

Source/cmAddCustomTargetCommand.cxx

@@ -159,12 +159,14 @@ bool cmAddCustomTargetCommand
     }
 
   // Enforce name uniqueness.
+  {
   std::string msg;
   if(!this->Makefile->EnforceUniqueName(args[0], msg))
     {
     this->SetError(msg.c_str());
     return false;
     }
+  }
 
   // Add the utility target to the makefile.
   bool escapeOldStyle = !verbatim;

Source/cmAddExecutableCommand.cxx

@@ -101,12 +101,14 @@ bool cmAddExecutableCommand
     }
 
   // Enforce name uniqueness.
+  {
   std::string msg;
   if(!this->Makefile->EnforceUniqueName(exename, msg))
     {
     this->SetError(msg.c_str());
     return false;
     }
+  }
 
   if (s == args.end())
     {

Source/cmAddLibraryCommand.cxx

@@ -128,12 +128,14 @@ bool cmAddLibraryCommand
     }
 
   // Enforce name uniqueness.
+  {
   std::string msg;
   if(!this->Makefile->EnforceUniqueName(libName, msg))
     {
     this->SetError(msg.c_str());
     return false;
     }
+  }
 
   if (s == args.end())
     {