doc: install libvlc samples in proper subdirectory

(cherry picked from commit 9cd19ad5d3daad87b4ec25a0a1c3bfdec31ff043)
Signed-off-by: Pierre Ynard <linkfanel@yahoo.fr>

doc/Makefile.am

@@ -12,8 +12,9 @@ LIBVLC_SAMPLES = \
 	libvlc/wx_player.cpp \
 	$(NULL)
 
+nobase_doc_DATA = $(LIBVLC_SAMPLES)
+
 doc_DATA = \
-	$(LIBVLC_SAMPLES) \
 	bugreport-howto.txt \
 	fortunes.txt \
 	intf-vcd.txt \