Add an explicit --disable-avahi to the configuration options.

Previous defaults remain --- the option must be explicitly
defined to be used. Thanks to E. Liddell.

configure.in.in

@@ -198,26 +198,31 @@ fi
 m4_pattern_allow(PKG_CONFIG_MIN_VERSION)
 PKG_PROG_PKG_CONFIG
 
-PKG_CHECK_MODULES( AVAHI,  avahi-client >= 0.6.10, 
+AC_ARG_WITH([avahi], AS_HELP_STRING([--without-avahi], [Build without avahi/ZeroConf support (default: test)]))
-[ 
+
-	AC_SUBST(AVAHI_CFLAGS)
+avahi=false
-	AC_SUBST(AVAHI_LIBS)
+if test "x$with_avahi" != "xno"; then
-	avahi=true
+ PKG_CHECK_MODULES( AVAHI,  avahi-client >= 0.6.10,
-],
+ [
-[
+   AC_SUBST(AVAHI_CFLAGS)
-	missing_avahi_warning=yes
+   AC_SUBST(AVAHI_LIBS)
-	avahi=false
+   avahi=true
-])
+ ],
-
+ [
-PKG_CHECK_MODULES( AVAHI_TQT,  avahi-tqt >= 0.6.10, 
+   missing_avahi_warning=yes
-[ 
+   avahi=false
-	AC_SUBST(AVAHI_TQT_CFLAGS)
+ ])
-	AC_SUBST(AVAHI_TQT_LIBS)
+
-	avahi=true
+ PKG_CHECK_MODULES( AVAHI_TQT,  avahi-tqt >= 0.6.10,
-],
+ [
-[
+   AC_SUBST(AVAHI_TQT_CFLAGS)
-	missing_avahi_warning=yes
+   AC_SUBST(AVAHI_TQT_LIBS)
-	avahi=false
+   avahi=true
-])
+ ],
+ [
+   missing_avahi_warning=yes
+   avahi=false
+ ])
+fi
 
 AM_CONDITIONAL(COMPILE_ZEROCONF, test x$avahi = xtrue)