Autogen: Define all macro names in CMAKE_AUTOMOC_MACRO_NAMES

Instead of adding `Q_OBJECT` and `Q_GADGET` to the macro search list
in `Source/cmQtAutoGenerators.cxx`, add them in
`Modules/CMakeGenericSystem.cmake` to the default value of
`CMAKE_AUTOMOC_MACRO_NAMES`.
Also add `Q_NAMESPACE` to `CMAKE_AUTOMOC_MACRO_NAMES`
which closes #17299.

Modules/CMakeGenericSystem.cmake

@@ -23,6 +23,7 @@ set(CMAKE_DL_LIBS "dl")
 
 set(CMAKE_FIND_LIBRARY_PREFIXES "lib")
 set(CMAKE_FIND_LIBRARY_SUFFIXES ".so" ".a")
+set(CMAKE_AUTOMOC_MACRO_NAMES "Q_OBJECT" "Q_GADGET" "Q_NAMESPACE")
 
 # basically all general purpose OSs support shared libs
 set_property(GLOBAL PROPERTY TARGET_SUPPORTS_SHARED_LIBS TRUE)

Source/cmQtAutoGenerators.cxx

@@ -149,12 +149,6 @@ cmQtAutoGenerators::cmQtAutoGenerators()
     }
   }
 
-  // Moc macro filters
-  this->MocMacroFilters.emplace_back(
-    "Q_OBJECT", "[\n][ \t]*{?[ \t]*Q_OBJECT[^a-zA-Z0-9_]");
-  this->MocMacroFilters.emplace_back(
-    "Q_GADGET", "[\n][ \t]*{?[ \t]*Q_GADGET[^a-zA-Z0-9_]");
-
   // Precompile regular expressions
   this->MocRegExpInclude.compile(
     "[\n][ \t]*#[ \t]*include[ \t]+"
@@ -326,7 +320,7 @@ bool cmQtAutoGenerators::InitInfoFile(cmMakefile* makefile,
         InfoGetList("AM_MOC_MACRO_NAMES");
       for (std::string const& item : MocMacroNames) {
         this->MocMacroFilters.emplace_back(
-          item, ("[^a-zA-Z0-9_]" + item).append("[^a-zA-Z0-9_]"));
+          item, ("[\n][ \t]*{?[ \t]*" + item).append("[^a-zA-Z0-9_]"));
       }
     }
     {