[libgweather] build: fix macOS dylib versioning

[Bastien Nocera <hadess src gnome org>]

commit dc7f4b7b72c27a9047b2441bf5bb7fe60108a543
Author: Tom Schoonjans <Tom Schoonjans diamond ac uk>
Date:   Mon Mar 11 17:53:56 2019 +0000

    build: fix macOS dylib versioning

 libgweather/meson.build | 1 +
 meson.build             | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)
---
diff --git a/libgweather/meson.build b/libgweather/meson.build
index 301e7e8..6688807 100644
--- a/libgweather/meson.build
+++ b/libgweather/meson.build
@@ -62,6 +62,7 @@ lib_libgweather = shared_library('gweather-3',
   include_directories: root_inc,
   dependencies: deps_libgweather,
   version: libgweather_so_version,
+  darwin_versions: libgweather_darwin_versions,
   install: true,
 )
 
diff --git a/meson.build b/meson.build
index eb27da4..5c3288b 100644
--- a/meson.build
+++ b/meson.build
@@ -1,6 +1,6 @@
 project('libgweather', 'c',
   version: '3.32.0',
-  meson_version: '>= 0.43.0',
+  meson_version: '>= 0.48.0',
 )
 
 libgweather_version = meson.project_version().split('.')
@@ -21,6 +21,10 @@ libgweather_lt_a=0
 libgweather_so_version = '@0@.@1@.@2@'.format((libgweather_lt_c - libgweather_lt_a),
                                             libgweather_lt_a, libgweather_lt_r)
 
+current = libgweather_lt_c - libgweather_lt_a
+interface_age = libgweather_lt_r
+libgweather_darwin_versions = [current + 1, '@0@.@1@'.format(current + 1, interface_age)]
+
 pkgconfig = import('pkgconfig')
 gnome = import('gnome')
 i18n = import('i18n')