Autogen: Deprecation message for CMAKE_AUTOMOC_RELAXED_MODE

`CMAKE_AUTOMOC_RELAXED_MODE` was added for backwards compatibility with KDE 4,
which had its last release in 2014.  It does not offer additional features
but complicates the `AUTOMOC` code and dependency computation considerably.

Projects that use `CMAKE_AUTOMOC_RELAXED_MODE` functionality always got
extensive warnings during builds and tips on how to convert to regular mode,
which is trivial (see commit e474dcb231, CMake 2.8.7).

It's time to consider this feature deprecated and issue a warning at
configuration time as well.

This adds a configuration time deprecation `AUTHOR_WARNING` for
`CMAKE_AUTOMOC_RELAXED_MODE`.

Source/cmQtAutoGenInitializer.cxx

@@ -407,6 +407,19 @@ bool cmQtAutoGenInitializer::InitCustomTargets()
         }
       }
     }
+
+    // CMAKE_AUTOMOC_RELAXED_MODE deprecation warning
+    if (this->Moc.Enabled) {
+      if (cmSystemTools::IsOn(
+            makefile->GetDefinition("CMAKE_AUTOMOC_RELAXED_MODE"))) {
+        std::string msg = "AUTOMOC: CMAKE_AUTOMOC_RELAXED_MODE is "
+                          "deprecated an will be removed in the future.  ";
+        msg += "Consider disabling it and converting the target ";
+        msg += this->Target->GetName();
+        msg += " to regular mode.";
+        makefile->IssueMessage(MessageType::AUTHOR_WARNING, msg);
+      }
+    }
   }
 
   // Init rcc specific settings

Source/cmQtAutoMocUic.cxx

@@ -708,7 +708,7 @@ bool cmQtAutoMocUic::JobEvaluateT::MocEvalSource(
         msg += Quoted(sourceFile.FileName);
         msg += "!\nBetter include ";
         msg += Quoted(sourceBase + ".moc");
-        msg += " for compatibility with strict mode.\n";
+        msg += " for compatibility with regular mode.\n";
         msg += "This is a CMAKE_AUTOMOC_RELAXED_MODE warning.\n";
         Log().WarningFile(GenT::MOC, sourceFile.FileName, msg);
       }
@@ -770,7 +770,7 @@ bool cmQtAutoMocUic::JobEvaluateT::MocEvalSource(
         msg += Quoted(header->FileName);
         msg += "!\nBetter include ";
         msg += Quoted("moc_" + incKey.Base + ".cpp");
-        msg += " for a compatibility with strict mode.\n";
+        msg += " for a compatibility with regular mode.\n";
         msg += "This is a CMAKE_AUTOMOC_RELAXED_MODE warning.\n";
         Log().WarningFile(GenT::MOC, sourceFile.FileName, msg);
       } else {
@@ -782,7 +782,7 @@ bool cmQtAutoMocUic::JobEvaluateT::MocEvalSource(
         msg += Quoted(header->FileName);
         msg += "!\nBetter include ";
         msg += Quoted("moc_" + incKey.Base + ".cpp");
-        msg += " for compatibility with strict mode.\n";
+        msg += " for compatibility with regular mode.\n";
         msg += "This is a CMAKE_AUTOMOC_RELAXED_MODE warning.\n";
         Log().WarningFile(GenT::MOC, sourceFile.FileName, msg);
       }
@@ -797,7 +797,7 @@ bool cmQtAutoMocUic::JobEvaluateT::MocEvalSource(
       // Check if this is the sources own .moc file
       bool const ownMoc = (incKey.Base == sourceBase);
       if (!ownMoc) {
-        // Don't allow <BASE>.moc include other than own in strict mode
+        // Don't allow <BASE>.moc include other than own in regular mode
         std::string msg = "The file includes the moc file ";
         msg += Quoted(incKey.Key);
         msg += ",\nwhich seems to be the moc file from a different "