[gnome-screenshot] honor the mandir option

[Jasper Lievisse Adriaanse <jasperla src gnome org>]

commit d93c043cdc9eb3259c331f6c534e970db858895f
Author: Jasper Lievisse Adriaanse <jasper humppa nl>
Date:   Thu Nov 2 12:36:08 2017 +0100

    honor the mandir option

 src/meson.build |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/meson.build b/src/meson.build
index 8fe9855..1fc6b1b 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -57,7 +57,7 @@ install_data('org.gnome.gnome-screenshot.gschema.xml',
              install_dir: gnome_screenshot_schemadir)
 
 install_data('gnome-screenshot.1',
-             install_dir: join_paths(gnome_screenshot_datadir, 'man', 'man1'))
+             install_dir: join_paths(get_option('mandir'), 'man1'))
 
 install_data('gnome-screenshot.convert',
              install_dir: join_paths(gnome_screenshot_datadir, 'GConf', 'gsettings'))