qt6-build.eclass: move CMAKE_QA_COMPAT_SKIP=1 to src_prepare

This was changed in cmake.eclass, could move it global but kind of
prefer to avoid this in an eclass and it has the minor bonus of
letting the src_install QA check still happen which we have no
reason to skip on such a large dev-qt/*:6 scale.

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

eclass/qt6-build.eclass

@@ -118,6 +118,9 @@ qt6-build_src_unpack() {
 # QT6_PREFIX, QT6_LIBDIR, and others), and handle anything else
 # generic as needed.
 qt6-build_src_prepare() {
+	# Qt has quite a lot of unused (false positive) CMakeLists.txt
+	local CMAKE_QA_COMPAT_SKIP=1
+
 	cmake_src_prepare
 
 	if [[ -e CMakeLists.txt ]]; then
@@ -178,9 +181,6 @@ qt6-build_src_configure() {
 		local mycmakeargs=("${defaultcmakeargs[@]}")
 	fi
 
-	# Qt has quite a lot of unused (false positive) CMakeLists.txt
-	local CMAKE_QA_COMPAT_SKIP=1
-
 	cmake_src_configure
 }