CMake: doctools: Avoid blocking integrations due to version mismatch

It can happen that qt repo version bumps are direct pushed, and not
merged in DAG-dependency order. This can cause a mismatch between the
qttools package version and any of its dependencies, which would block
integrations. To avoid this, we disable the warning about incompatible
package versions when building the doc tools. The version check in
that case doesn't make sense, so it's safe to do.

Amends f7f02c791bcbee44597f1fe24570ebdf352ec648

Task-number: QTBUG-128730
Change-Id: I6180ecb09c6a3dee415ae73c11549ee0f709f240
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Toni Saario <toni.saario@qt.io>
(cherry picked from commit a8f55f4729918700b9597843c98f9f2505ff0d23)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 81b3e808403253bcfa34e071d70c046ee6c4b574)

cmake/QtBuildStaticDocToolsScript.cmake

@@ -178,6 +178,10 @@ function(qt_internal_configure_qt)
             -skip qtactiveqt,qtimageformats,qtlanguageserver,qtsvg
             --
             -DWARNINGS_ARE_ERRORS=OFF
+            # When 6.x.y version bumps are not merged in DAG-dependency order, this avoids
+            # blocking integrations due to mismatch of qtools package version and any of its
+            # dependencies.
+            -DQT_NO_PACKAGE_VERSION_INCOMPATIBLE_WARNING=ON
             --log-level STATUS
             --fresh
             -GNinja