gen_version.py: use preview_minor to override release minor for preview releases

In latest-release.json, for a preview release branch, set preview_minor to the preview version so that the released dxil version doesn't change, but gen_version.py has something to override the minor version for binary file versioning.

Author: tex3d

utils/version/gen_version.py

@@ -80,7 +80,13 @@ def rc_version_field_1(self):
         return self.latest_release_info["version"]["major"]
 
     def rc_version_field_2(self):
-        return self.latest_release_info["version"]["minor"]
+        minor = self.latest_release_info["version"]["minor"]
+        # If this is a preview branch, we use the preview_minor field as the
+        # minor version in the RC file. This allows us to have a different
+        # minor version for preview releases, without changing the highest
+        # released minor version.
+        minor = self.latest_release_info["version"].get("preview_minor", minor)
+        return minor
 
     def rc_version_field_3(self):
         return self.latest_release_info["version"]["rev"] if self.options.official else "0"