configure.ac: use MPD_ENABLE_AUTO_PKG_LIB for libgme

Makefile.am

@@ -1017,7 +1017,7 @@ libdecoder_a_SOURCES += \
 	src/decoder/plugins/SndfileDecoderPlugin.hxx
 endif
 
-if HAVE_GME
+if ENABLE_GME
 libdecoder_a_SOURCES += \
 	src/decoder/plugins/GmeDecoderPlugin.cxx src/decoder/plugins/GmeDecoderPlugin.hxx
 endif

configure.ac

@@ -328,11 +328,6 @@ AC_ARG_ENABLE(fifo,
 		[disable support for writing audio to a FIFO (default: enable)]),,
 	enable_fifo=yes)
 
-AC_ARG_ENABLE(gme,
-	AS_HELP_STRING([--enable-gme],
-		[enable Blargg's game music emulator plugin]),,
-	enable_gme=auto)
-
 AC_ARG_ENABLE(httpd-output,
 	AS_HELP_STRING([--enable-httpd-output],
 		[enables the HTTP server output]),,
@@ -894,12 +889,10 @@ MPD_ENABLE_AUTO_PKG(fluidsynth, FLUIDSYNTH, [fluidsynth >= 1.1],
 	[fluidsynth MIDI decoder plugin], [fluidsynth not found])
 
 dnl ---------------------------------- libgme ---------------------------------
-MPD_AUTO_PKG_LIB(gme, GME, [libgme], gme, gme_open_file, [-lgme -lstdc++], [],
-	[gme decoder plugin], [libgme not found])
-AM_CONDITIONAL(HAVE_GME, test x$enable_gme = xyes)
-if test x$enable_gme = xyes; then
-	AC_DEFINE(HAVE_GME, 1, [Define for gme support])
-fi
+
+MPD_ENABLE_AUTO_PKG_LIB(gme, GME, [libgme],
+	gme, gme_open_file, [-lgme -lstdc++], [],
+	[Game Music Emulator decoder plugin], [libgme not found])
 
 dnl ---------------------------------- libmad ---------------------------------
 MPD_ENABLE_AUTO_PKG_LIB(mad, MAD, [mad],

src/decoder/DecoderList.cxx

@@ -104,7 +104,7 @@ const struct DecoderPlugin *const decoder_plugins[] = {
 #ifdef ENABLE_FFMPEG
 	&ffmpeg_decoder_plugin,
 #endif
-#ifdef HAVE_GME
+#ifdef ENABLE_GME
 	&gme_decoder_plugin,
 #endif
 	&pcm_decoder_plugin,