gui-libs/kddockwidgets: fix build with Qt 6.10 + add := operator

I've missed that this was using Private bits, and thankfully Qt now
makes these harder to miss (albeit breaks build).

Also use ${PF} for doc deletion, hadn't noticed this uses the actual
cmake.eclass provided path and appends -qt6 to it. That it appends
turns out convenient for deletion given this only installs licenses
plus a README that is already installed by the eclass' einstalldocs.

Signed-off-by: Ionen Wolkens <ionen@gentoo.org>

gui-libs/kddockwidgets/files/kddockwidgets-2.2.5-qt610.patch

@@ -0,0 +1,14 @@
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -184,2 +184,5 @@
+         find_package(Qt${QT_VERSION_MAJOR} ${QT_MIN_VERSION} NO_MODULE REQUIRED COMPONENTS Widgets)
++        if (Qt${QT_VERSION_MAJOR}_VERSION VERSION_GREATER_EQUAL 6.10)
++            find_package(Qt${QT_VERSION_MAJOR} ${QT_MIN_VERSION} NO_MODULE REQUIRED COMPONENTS WidgetsPrivate)
++        endif()
+         set(KDDW_FRONTEND_QTWIDGETS ON)
+@@ -189,2 +192,5 @@
+         find_package(Qt${QT_VERSION_MAJOR} ${QT_MIN_VERSION} NO_MODULE REQUIRED COMPONENTS Quick QuickControls2)
++        if (Qt${QT_VERSION_MAJOR}_VERSION VERSION_GREATER_EQUAL 6.10)
++            find_package(Qt${QT_VERSION_MAJOR} ${QT_MIN_VERSION} NO_MODULE REQUIRED COMPONENTS QuickPrivate)
++        endif()
+         set(KDDW_FRONTEND_QTQUICK ON)

gui-libs/kddockwidgets/kddockwidgets-2.2.5-r1.ebuild

@@ -17,9 +17,10 @@ IUSE="qml"
 # building tests require developer mode which is messy to enable here
 RESTRICT="test"
 
+# uses Qt private APIs wrt :=
 RDEPEND="
-	dev-qt/qtbase:6[widgets]
-	qml? ( dev-qt/qtdeclarative:6 )
+	dev-qt/qtbase:6=[widgets]
+	qml? ( dev-qt/qtdeclarative:6= )
 "
 DEPEND="
 	${DEPEND}
@@ -28,6 +29,7 @@ DEPEND="
 
 PATCHES=(
 	"${FILESDIR}"/${PN}-2.2.1-include-paths.patch
+	"${FILESDIR}"/${PN}-2.2.5-qt610.patch
 )
 
 src_configure() {
@@ -45,5 +47,6 @@ src_configure() {
 src_install() {
 	cmake_src_install
 
-	rm -r -- "${ED}"/usr/share/doc/${P}-qt6 || die
+	# only has licenses and duplicate files
+	rm -r -- "${ED}"/usr/share/doc/${PF}-qt6 || die
 }