[libwnck] build: Support new GNOME versioning schema

[Marco Trevisan <marcotrevi src gnome org>]

commit c823cd3d70f60986a9f12cbb8143b4049b9ea496
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Mon May 10 18:56:45 2021 +0200

    build: Support new GNOME versioning schema
    
    alpha, beta and rc releases can will be exposed source side as:
       major: MAJOR_VERSION-1
       minor: 99-MINOR_VERSION_LEVEL
       micro: MICRO_VERSION
    
    So that:
       40.alpha => 39.97.0
       40.alpha.1 => 39.97.1
       40.beta => 39.98.0
       40.beta.1 => 39.98.1
       40.rc => 39.99.0
       40.rc.1 => 39.99.1
       40.0 => 40.0.0
       40.1 => 40.1.0

 libwnck/meson.build | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)
---
diff --git a/libwnck/meson.build b/libwnck/meson.build
index 04f30d6..eef9de5 100644
--- a/libwnck/meson.build
+++ b/libwnck/meson.build
@@ -4,9 +4,29 @@ libwnck_includedir = join_paths(PACKAGE_NAME, meson.project_name())
 
 version_data = configuration_data()
 version_array = meson.project_version().split('.')
-version_data.set('WNCK_MAJOR_VERSION', version_array[0])
-version_data.set('WNCK_MINOR_VERSION', version_array[1])
-version_data.set('WNCK_MICRO_VERSION', version_array[2])
+
+major_version = version_array[0].to_int()
+minor_version = version_array[1]
+micro_version = (version_array.length() == 3) ? version_array[2].to_int() : 0
+
+if minor_version == 'alpha'
+  minor_version = 97
+elif minor_version == 'beta'
+  minor_version = 98
+elif minor_version == 'rc'
+  minor_version = 99
+else
+  # Ensure that only numbers are expected in this case
+  minor_version = minor_version.to_int()
+endif
+
+if minor_version >= 97
+  major_version = major_version - 1
+endif
+
+version_data.set('WNCK_MAJOR_VERSION', major_version)
+version_data.set('WNCK_MINOR_VERSION', minor_version)
+version_data.set('WNCK_MICRO_VERSION', micro_version)
 
 headers = [
   'libwnck.h',