[gnome-bluetooth] build: Set prefix-relative install_dir for pkgconfig

[Bastien Nocera <hadess src gnome org>]

commit b20fb34bf44310fba91fc1843baf9544c44cf41f
Author: Iñigo Martínez <inigomartinez gmail com>
Date:   Tue Nov 14 16:10:29 2017 +0100

    build: Set prefix-relative install_dir for pkgconfig
    
    While installing seems to have no issues with absolute paths
    for install_dir, the pkgconfig integration in meson does
    and create wrong library paths in the .pc file.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=790332

 lib/meson.build |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/lib/meson.build b/lib/meson.build
index 17fcbf2..c2cc52b 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -123,7 +123,7 @@ pkg.generate(
   ],
   requires_private: 'libudev',
   variables: 'exec_prefix=' + gnomebt_libexecdir,
-  install_dir: join_paths(gnomebt_libdir, 'pkgconfig')
+  install_dir: join_paths(get_option('libdir'), 'pkgconfig')
 )
 
 if enable_gir