Fix asa subtitles merge. Close #1468

Patch by aballier.

configure.ac

@@ -3840,7 +3840,7 @@ dnl asa demuxer
 dnl
 AC_ARG_ENABLE(asademux,
   [  --enable-asademux      asa subtitle demuxing (default disabled)])
-AS_IF( [test "${enable_asa}" != "no"], [
+AS_IF( [test "${enable_asademux}" != "no"], [
   PKG_CHECK_MODULES(PCRE,
       libpcre >= 6.5,
       [

modules/demux/Modules.am

@@ -18,7 +18,7 @@ SOURCES_pva = pva.c
 SOURCES_aiff = aiff.c
 SOURCES_mjpeg = mjpeg.c
 SOURCES_subtitle = subtitle.c
-SOURCES_asademux = subtitle_asa.c asademux.c
+SOURCES_asademux = subtitle_asa.c asademux.c asademux_defs.h asademux.h
 SOURCES_ty = ty.c ../codec/cc.h
 SOURCES_vobsub = vobsub.c
 SOURCES_voc = voc.c