OSS: fix Makefile typo

modules/access/Modules.am

@@ -92,7 +92,7 @@ libvlc_LTLIBRARIES += \
 	libaccess_vdr_plugin.la \
 	$(NULL)
 
-libaccess_oss_plugin_la = oss.c
+libaccess_oss_plugin_la_SOURCES = oss.c
 libaccess_oss_plugin_la_LIBADD = $(AM_LIBADD) $(OSS_LIBS)
 libaccess_oss_plugin_la_DEPENDENCIES =
 if HAVE_OSS

modules/audio_output/Modules.am

@@ -9,7 +9,7 @@ SOURCES_audioqueue = audioqueue.c
 
 libvlc_LTLIBRARIES += libaout_file_plugin.la
 
-liboss_plugin_la = oss.c
+liboss_plugin_la_SOURCES = oss.c
 liboss_plugin_la_LIBADD = $(AM_LIBADD) $(OSS_LIBS)
 liboss_plugin_la_DEPENDENCIES =
 if HAVE_OSS