cmListFileBacktrace: Internalize the step of making paths relative.

Currently cmMakefile calls MakeRelative on a copy of the backtrace,
emits the copy to the stream once, then discards the copy.  There
is no need to have API for the path conversion.

Source/cmListFileCache.cxx

@@ -405,29 +405,17 @@ void cmListFileBacktrace::Append(cmListFileContext const& context)
   this->push_back(context);
 }
 
-//----------------------------------------------------------------------------
-void cmListFileBacktrace::MakeRelative()
-{
-  if (this->Relative)
-    {
-    return;
-    }
-  for (cmListFileBacktrace::iterator i = this->begin();
-       i != this->end(); ++i)
-    {
-    i->FilePath = this->LocalGenerator->Convert(i->FilePath,
-                                                cmLocalGenerator::HOME);
-    }
-  this->Relative = true;
-}
-
 void cmListFileBacktrace::PrintTitle(std::ostream& out)
 {
   if (this->empty())
     {
     return;
     }
-  out << (this->front().Line ? " at " : " in ") << this->front();
+
+  cmListFileContext lfc = this->front();
+  lfc.FilePath = this->LocalGenerator->Convert(lfc.FilePath,
+                                               cmLocalGenerator::HOME);
+  out << (lfc.Line ? " at " : " in ") << lfc;
 }
 
 void cmListFileBacktrace::PrintCallStack(std::ostream& out)
@@ -441,7 +429,9 @@ void cmListFileBacktrace::PrintCallStack(std::ostream& out)
   out << "Call Stack (most recent call first):\n";
   while(i != this->end())
     {
-    cmListFileContext const& lfc = *i;
+    cmListFileContext lfc = *i;
+    lfc.FilePath = this->LocalGenerator->Convert(lfc.FilePath,
+                                                 cmLocalGenerator::HOME);
     out << "  " << lfc << "\n";
     ++i;
     }

Source/cmListFileCache.h

@@ -76,19 +76,15 @@ class cmListFileBacktrace: private std::vector<cmListFileContext>
   public:
     cmListFileBacktrace(cmLocalGenerator* localGen = 0)
       : LocalGenerator(localGen)
-      , Relative(localGen ? false : true)
     {
     }
 
     void Append(cmListFileContext const& context);
 
-    void MakeRelative();
-
     void PrintTitle(std::ostream& out);
     void PrintCallStack(std::ostream& out);
   private:
     cmLocalGenerator* LocalGenerator;
-    bool Relative;
 };
 
 struct cmListFile

Source/cmake.cxx

@@ -2519,7 +2519,6 @@ void cmake::IssueMessage(cmake::MessageType t, std::string const& text,
                          cmListFileBacktrace const& bt)
 {
   cmListFileBacktrace backtrace = bt;
-  backtrace.MakeRelative();
 
   std::ostringstream msg;
   if (!this->PrintMessagePreamble(t, msg))