Fix underquoted defintion warnings from newer automake

git-svn-id: https://svn.musicpd.org/mpd/trunk@4352 09075e82-0dd4-0310-85a5-a0d7c8717e4f

m4/ao.m4

@@ -6,7 +6,7 @@
 dnl XIPH_PATH_AO([ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND]])
 dnl Test for libao, and define AO_CFLAGS and AO_LIBS
 dnl
-AC_DEFUN(XIPH_PATH_AO,
+AC_DEFUN([XIPH_PATH_AO],
 [dnl 
 dnl Get the cflags and libraries
 dnl

m4/libFLAC.m4

@@ -4,7 +4,7 @@
 dnl AM_PATH_LIBFLAC([ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND]])
 dnl Test for libFLAC, and define LIBFLAC_CFLAGS and LIBFLAC_LIBS
 dnl
-AC_DEFUN(AM_PATH_LIBFLAC,
+AC_DEFUN([AM_PATH_LIBFLAC],
 [dnl 
 dnl Get the cflags and libraries
 dnl

m4/libmikmod.m4

@@ -8,7 +8,7 @@ dnl AM_PATH_LIBMIKMOD([MINIMUM-VERSION, [ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND
 dnl Test for libmikmod, and define LIBMIKMOD_CFLAGS, LIBMIKMOD_LIBS and
 dnl LIBMIKMOD_LDADD
 dnl
-AC_DEFUN(AM_PATH_LIBMIKMOD,
+AC_DEFUN([AM_PATH_LIBMIKMOD],
 [dnl 
 dnl Get the cflags and libraries from the libmikmod-config script
 dnl

m4/ogg.m4

@@ -5,7 +5,7 @@
 dnl XIPH_PATH_OGG([ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND]])
 dnl Test for libogg, and define OGG_CFLAGS and OGG_LIBS
 dnl
-AC_DEFUN(XIPH_PATH_OGG,
+AC_DEFUN([XIPH_PATH_OGG],
 [dnl 
 dnl Get the cflags and libraries
 dnl

m4/vorbis.m4

@@ -6,7 +6,7 @@
 dnl XIPH_PATH_VORBIS([ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND]])
 dnl Test for libvorbis, and define VORBIS_CFLAGS and VORBIS_LIBS
 dnl
-AC_DEFUN(XIPH_PATH_VORBIS,
+AC_DEFUN([XIPH_PATH_VORBIS],
 [dnl 
 dnl Get the cflags and libraries
 dnl