ENH: Improve error message when installation file(CHRPATH) cannot change the RPATH.

Source/cmFileCommand.cxx

@@ -1407,8 +1407,10 @@ bool cmFileCommand::HandleChrpathCommand(std::vector<std::string> const& args)
   else
     {
     cmOStringStream e;
-    e << "CHRPATH could not write new RPATH \""
-      << newRPath << "\" to the file \"" << file << "\": "
+    e << "CHRPATH could not write new RPATH:\n"
+      << "  " << newRPath << "\n"
+      << "to the file:\n"
+      << "  " << file << "\n"
       << emsg;
     this->SetError(e.str().c_str());
     return false;

Source/cmSystemTools.cxx

@@ -2229,7 +2229,13 @@ bool cmSystemTools::ChangeRPath(std::string const& file,
         }
       if(emsg)
         {
-        *emsg = "The current RPATH does not begin with that specified.";
+        cmOStringStream e;
+        e << "The current RPATH is:\n"
+          << "  " << se->Value << "\n"
+          << "which does not begin with:\n"
+          << "  " << oldRPath << "\n"
+          << "as was expected.";
+        *emsg = e.str();
         }
       return false;
       }