[nautilus] configure: bump gtk min version

[Carlos Soriano Sánchez <csoriano src gnome org>]

commit ff61b06f17cb00b6d09a7944e81f034a0b610aca
Author: Carlos Soriano <csoriano gnome org>
Date:   Mon Nov 23 11:32:40 2015 +0100

    configure: bump gtk min version
    
    For behave accordingly with gtkplacessidebar and gtkplacesview.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index efcc1b3..4af1f29 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5,7 +5,7 @@ dnl ===========================================================================
 m4_define(glib_minver,                 2.45.7)
 m4_define(gnome_desktop_minver,        3.0.0)
 m4_define(pango_minver,                1.28.3)
-m4_define(gtk_minver,                  3.17.5)
+m4_define(gtk_minver,                  3.18.5)
 m4_define(xml_minver,                  2.7.8)
 m4_define(exif_minver,                 0.6.20)
 m4_define(exempi_minver,               2.1.0)