[gedit] build: simplify meson.add_install_script() call

[Sébastien Wilmet <swilmet src gnome org>]

commit 10bba2543a25e2859686e5b546741f40bf2025f5
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Mon Mar 16 13:50:41 2020 +0100

    build: simplify meson.add_install_script() call
    
    join_paths() is deprecated.

 meson.build | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/meson.build b/meson.build
index ace86d91d..ba4d6debc 100644
--- a/meson.build
+++ b/meson.build
@@ -100,8 +100,8 @@ endif
 
 meson.add_install_script(
   'build-aux/meson/post_install.py',
-  join_paths(get_option('prefix'), get_option('libdir')),
-  join_paths(get_option('prefix'), get_option('datadir'))
+  get_option('prefix') / get_option('libdir'),
+  get_option('prefix') / get_option('datadir')
 )
 
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