[gnome-todo] project: don't build Todo.txt by default

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit b2cbdf4efd3db7a5e0f8cff0f849bf67749c5895
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Sat Apr 22 11:30:48 2017 -0300

    project: don't build Todo.txt by default
    
    It's still experimental, and we might not want our
    users to face issues.

 configure.ac    |    2 +-
 src/Makefile.am |   10 +++++++---
 2 files changed, 8 insertions(+), 4 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 5bd627d..22bc04e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -94,7 +94,7 @@ GNOME_TODO_ADD_PLUGIN([scheduled-panel], [Scheduled Panel], [yes])
 GNOME_TODO_ADD_PLUGIN([score], [Score], [yes])
 GNOME_TODO_ADD_PLUGIN([today-panel], [Today Panel], [yes])
 GNOME_TODO_ADD_PLUGIN([unscheduled-panel], [Unscheduled Tasks Panel], [yes])
-GNOME_TODO_ADD_PLUGIN([todo-txt], [Todo.Txt], [yes])
+GNOME_TODO_ADD_PLUGIN([todo-txt], [Todo.Txt], [no])
 
 
 dnl ***********************************************************************
diff --git a/src/Makefile.am b/src/Makefile.am
index c7be054..1dd5749 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -103,7 +103,6 @@ gnome_todo_LDFLAGS = \
        -Wl,--undefined=gtd_plugin_dark_theme_register_types \
        -Wl,--undefined=gtd_plugin_scheduled_panel_register_types \
        -Wl,--undefined=gtd_plugin_today_panel_register_types \
-       -Wl,--undefined=gtd_plugin_todo_txt_register_types \
        -lm \
        $(GNOME_TODO_WARN_LDFLAGS)
 
@@ -113,7 +112,6 @@ gnome_todo_LDADD = \
        $(top_builddir)/plugins/dark-theme/libdarktheme.la \
        $(top_builddir)/plugins/scheduled-panel/libscheduledpanel.la \
        $(top_builddir)/plugins/today-panel/libtodaypanel.la \
-       $(top_builddir)/plugins/todo-txt/libtodotxt.la \
        $(GNOME_TODO_LIBS)
 
 gnome_todo_DEPENDENCIES = \
@@ -121,7 +119,13 @@ gnome_todo_DEPENDENCIES = \
        $(top_builddir)/plugins/dark-theme/libdarktheme.la \
        $(top_builddir)/plugins/scheduled-panel/libscheduledpanel.la \
        $(top_builddir)/plugins/today-panel/libtodaypanel.la \
-        $(top_builddir)/plugins/todo-txt/libtodotxt.la
+       $(NULL)
+
+if BUILD_TODO_TXT_PLUGIN
+gnome_todo_LDFLAGS += -Wl,--undefined=gtd_plugin_todo_txt_register_types
+gnome_todo_LDADD += $(top_builddir)/plugins/todo-txt/libtodotxt.la
+gnome_todo_DEPENDENCIES += $(top_builddir)/plugins/todo-txt/libtodotxt.la
+endif
 
 #
 # Export headers to [PREFIX]/include/gnome-todo