QFreeList: Resolve symbol ambiguity in unity build

Remove 'qfreelist.cpp' from the NO_UNITY_BUILD_SOURCES section
and fix the underlying problem of the clashing symbols with
'qabstracteventdispatcher.cpp', by wrapping the unnamed enum in
a namespace.

Amends: a07426d23a.

Task-number: QTBUG-109394
Pick-to: 6.6 6.5
Change-Id: I585ab06a33d46a11a48220f504c53a5f4fa91d7e
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

src/corelib/CMakeLists.txt

@@ -310,7 +310,6 @@ qt_internal_add_module(Core
         tools/qvector.h
         tools/qversionnumber.cpp tools/qversionnumber.h
     NO_UNITY_BUILD_SOURCES
-        tools/qfreelist.cpp # Size0/Offset0 (also in qabstracteventdispatcher.cpp)
         # MinGW complains about `free-nonheap-object` in ~QSharedDataPointer()
         # despite the fact that appropriate checks are in place to avoid that!
         tools/qshareddata.cpp tools/qshareddata.h

src/corelib/tools/qfreelist.cpp

@@ -6,6 +6,7 @@
 QT_BEGIN_NAMESPACE
 
 // default sizes and offsets (no need to define these when customizing)
+namespace QFreeListDefaultConstantsPrivate {
 enum {
     Offset0 = 0x00000000,
     Offset1 = 0x00008000,
@@ -17,12 +18,13 @@ enum {
     Size2 = Offset3 - Offset2,
     Size3 = QFreeListDefaultConstants::MaxIndex - Offset3
 };
+}
 
 Q_CONSTINIT const int QFreeListDefaultConstants::Sizes[QFreeListDefaultConstants::BlockCount] = {
-    Size0,
-    Size1,
-    Size2,
-    Size3
+    QFreeListDefaultConstantsPrivate::Size0,
+    QFreeListDefaultConstantsPrivate::Size1,
+    QFreeListDefaultConstantsPrivate::Size2,
+    QFreeListDefaultConstantsPrivate::Size3
 };
 
 QT_END_NAMESPACE