configure.ac: expose variables OPENAL_CFLAGS and OPENAL_LIBS

Don't add these to the global MPD_CFLAGS and MPD_LIBS.  This allows
test programs to link without libopenal.

Makefile.am

@@ -599,6 +599,7 @@ OUTPUT_CFLAGS = \
 	$(AO_CFLAGS) \
 	$(ALSA_CFLAGS) \
 	$(JACK_CFLAGS) \
+	$(OPENAL_CFLAGS) \
 	$(PULSE_CFLAGS) \
 	$(SHOUT_CFLAGS)
 
@@ -606,6 +607,7 @@ OUTPUT_LIBS = \
 	$(AO_LIBS) \
 	$(ALSA_LIBS) \
 	$(JACK_LIBS) \
+	$(OPENAL_LIBS) \
 	$(PULSE_LIBS) \
 	$(SHOUT_LIBS)
 

configure.ac

@@ -829,6 +829,9 @@ fi
 
 AM_CONDITIONAL(HAVE_OSS, test x$enable_oss = xyes)
 
+AC_SUBST(OPENAL_CFLAGS,"")
+AC_SUBST(OPENAL_LIBS,"")
+
 if test x$enable_openal = xyes; then
 	if test x$enable_osx = xyes; then
 		AC_CHECK_HEADERS([OpenAL/al.h OpenAL/alc.h], [], [enable_openal=no])
@@ -845,11 +848,6 @@ if test x$enable_openal = xyes; then
 	fi
 fi
 
-if test x$enable_openal = xyes; then
-	MPD_CFLAGS="$MPD_CFLAGS $OPENAL_CFLAGS"
-	MPD_LIBS="$MPD_LIBS $OPENAL_LIBS"
-fi
-
 AM_CONDITIONAL(HAVE_OPENAL, test x$enable_openal = xyes)
 
 if test x$enable_fifo = xyes; then