qt5.inc: extend FILES_${PN}-examples-*

this fix :
ERROR: QA Issue: non debug package contains .debug directory: qtquick1-examples path
/work/armv7a-vfp-neon-oe-linux-gnueabi/qtquick1/5.1.1-r0/packages-split/qtquick1-examples/
usr/share/qt5/examples/declarative/cppextensions/plugins/org/qtproject/TimeExample/.debug/libqmlqtimeexampleplugin.so

Signed-off-by: Eric Bénard <eric@eukrea.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>