Don't assume the existence of QT_MAJOR_VERSION.

Also handle Qt5SrcTools_MAJOR_VERSION.

Modules/AutomocInfo.cmake.in

@@ -10,4 +10,5 @@ set(AM_QT_MOC_EXECUTABLE "@QT_MOC_EXECUTABLE@")
 set(AM_CMAKE_CURRENT_SOURCE_DIR "@CMAKE_CURRENT_SOURCE_DIR@/")
 set(AM_CMAKE_CURRENT_BINARY_DIR "@CMAKE_CURRENT_BINARY_DIR@/")
 set(AM_QT_VERSION_MAJOR "@QT_VERSION_MAJOR@" )
+set(AM_Qt5SrcTools_VERSION_MAJOR "@Qt5SrcTools_VERSION_MAJOR@" )
 set(AM_TARGET_NAME "@_moc_target_name@")

Source/cmQtAutomoc.cxx

@@ -51,6 +51,10 @@ void cmQtAutomoc::SetupAutomocTarget(cmTarget* target)
   const char* targetName = target->GetName();
   // don't do anything if there is no Qt4:
   std::string qtMajorVersion = makefile->GetSafeDefinition("QT_VERSION_MAJOR");
+  if (qtMajorVersion == "")
+    {
+      qtMajorVersion = makefile->GetSafeDefinition("Qt5SrcTools_VERSION_MAJOR");
+    }
   if (qtMajorVersion != "4" && qtMajorVersion != "5")
     {
     return;
@@ -215,6 +219,10 @@ bool cmQtAutomoc::ReadAutomocInfoFile(cmMakefile* makefile,
     }
 
   this->QtMajorVersion = makefile->GetSafeDefinition("AM_QT_VERSION_MAJOR");
+  if (this->QtMajorVersion == "")
+    {
+    this->QtMajorVersion = makefile->GetSafeDefinition("AM_Qt5SrcTools_VERSION_MAJOR");
+    }
   this->Sources = makefile->GetSafeDefinition("AM_SOURCES");
   this->Headers = makefile->GetSafeDefinition("AM_HEADERS");
   this->IncludeProjectDirsBefore = makefile->IsOn(