ptest: remove references to destination directory

Tests are build against the destination directory where qt module was
just installed. This causes extra files to be taken into source package
and adds references to the TMPDIR, which produces QA warnings from
buildpaths QA test. Use DEBUG_PREFIX_MAP to get rid of those paths.

Pick-to: 6.4 6.3 6.2
Task-number: QTBUG-105913
Change-Id: I01ed9261004410db307f2cd809a181377b734c9e
Reviewed-by: Ari Parkkila <ari.parkkila@qt.io>

recipes-qt/qt6/qt6-ptest.inc

@@ -6,6 +6,10 @@ inherit ptest
 QT_PTEST_ENABLED ?= "${@bb.utils.contains('DISTRO_FEATURES', 'ptest', '1', '0', d)}"
 PTEST_ENABLED = "${QT_PTEST_ENABLED}"
 
+DEBUG_PREFIX_MAP += "\
+ -fmacro-prefix-map=${D}= \
+"
+
 fakeroot do_install_ptest() {
     cat >${WORKDIR}/toolchain-ptest.cmake <<EOF
 include(${WORKDIR}/toolchain.cmake)