Makefile.am: fix installation regression

Automake doesn't generate automatic rules when a rule already exist in
the file, except if it cannot detect it. Adding the
`install-fooLTLIBRARIES: install-pkglibLTLIBRARIES` rule for audio
outputs, video outputs and vdpau broke the installation.

Adding `$(install-fooLTLIBRARIES): install-pkglibLTLIBRARIES` also makes
automake unhappy because of the variable name looking suspiciously close
to the target it generates, so a version without the dash is used for
the variable name in the rule. With this, the install target is
preserved but the dependency also exists in the output.

modules/audio_output/Makefile.am

@@ -2,7 +2,8 @@ aoutdir = $(pluginsdir)/audio_output
 aout_LTLIBRARIES =
 # Install the pkglib/pkglibexec first before relinking the modules.
 # This ensures libtool re-linking is not racy.
-install-aoutLTLIBRARIES: install-pkglibLTLIBRARIES
+installaoutLTLIBRARIES = install-aoutLTLIBRARIES
+$(installaoutLTLIBRARIES): install-pkglibLTLIBRARIES
 
 libvlc_android_audioformat_jni_la_SOURCES = \
 	audio_output/android/audioformat_jni.c \

modules/hw/vdpau/Makefile.am

 vdpaudir = $(pluginsdir)/vdpau
 # Install the pkglib/pkglibexec first before relinking the modules.
 # This ensures libtool re-linking is not racy.
-install-vpdauLTLIBRARIES: install-pkglibLTLIBRARIES
+installvpdauLTLIBRARIES = install-vdpauLTLIBRARIES
+$(installvpdauLTLIBRARIES): install-pkglibLTLIBRARIES
 
 
 libvlc_vdpau_la_SOURCES = hw/vdpau/vlc_vdpau.c hw/vdpau/vlc_vdpau.h

modules/video_output/Makefile.am

@@ -2,7 +2,8 @@ voutdir = $(pluginsdir)/video_output
 vout_LTLIBRARIES =
 # Install the pkglib/pkglibexec first before relinking the modules.
 # This ensures libtool re-linking is not racy.
-install-voutLTLIBRARIES: install-pkglibLTLIBRARIES
+installvoutLTLIBRARIES = install-voutLTLIBRARIES
+$(installvoutLTLIBRARIES): install-pkglibLTLIBRARIES
 
 EXTRA_DIST += video_output/README