meta-toolchain-qt: put QT_CONF_PATH in environment script

This will allow apps using QLibraryInfo class to find qt.conf.

[YOCTO #5339]

(From OE-Core master rev: fffa4c37c49b169f663d28612b9251819cef9577)

(From OE-Core rev: 6dbad65ed81a8ff80a965351dd9f229be51ca477)

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-qt/meta/meta-toolchain-qt.inc

@@ -24,6 +24,7 @@ toolchain_create_sdk_env_script_append() {
     echo 'export OE_QMAKE_QDBUSXML2CPP=${QT_TOOLS_PREFIX}/qdbusxml2cpp4' >> $script
     echo 'export OE_QMAKE_QT_CONFIG=${SDKTARGETSYSROOT}/${datadir}/${QT_DIR_NAME}/mkspecs/qconfig.pri' >> $script
     echo 'export QMAKESPEC=${SDKTARGETSYSROOT}/${datadir}/${QT_DIR_NAME}/mkspecs/linux-g++' >> $script
+    echo 'export QT_CONF_PATH=${SDKPATHNATIVE}/${sysconfdir}/qt.conf' >> $script
 
     # make a symbolic link to mkspecs for compatibility with Nokia's SDK
     # and QTCreator