doc: fix broken meson deps for various manuals outputs

This is incredibly haunted, but it can happen that you change libutil,
breaking the generation of the .json files, which then does not rebuild
the files. I don't expect they are slow to build, so it does not seem so
bad to just rebuild them every time instead of extracting a list of all
the possible deps.

We want to delete this nonsense anyway and replace it with generated
code.

Change-Id: Ia576d1a3bdee48fbaefbb5ac194354428d179a84

doc/manual/meson.build

@@ -20,6 +20,8 @@ conf_file_json = custom_target(
   capture : true,
   output : 'conf-file.json',
   env : nix_env_for_docs,
+  # FIXME: put the actual lib targets in here? meson have introspection challenge 2024 though.
+  build_always_stale : true,
 )
 
 nix_conf_file_md_body = custom_target(
@@ -50,6 +52,8 @@ nix_exp_features_json = custom_target(
   command : [ nix, '__dump-xp-features' ],
   capture : true,
   output : 'xp-features.json',
+  # FIXME: put the actual lib targets in here? meson have introspection challenge 2024 though.
+  build_always_stale : true,
 )
 
 language_json = custom_target(
@@ -57,6 +61,8 @@ language_json = custom_target(
   output : 'language.json',
   capture : true,
   env : nix_env_for_docs,
+  # FIXME: put the actual lib targets in here? meson have introspection challenge 2024 though.
+  build_always_stale : true,
 )
 
 nix3_cli_json = custom_target(
@@ -64,6 +70,8 @@ nix3_cli_json = custom_target(
   capture : true,
   output : 'nix.json',
   env : nix_env_for_docs,
+  # FIXME: put the actual lib targets in here? meson have introspection challenge 2024 though.
+  build_always_stale : true,
 )
 
 generate_manual_deps = files(

doc/manual/src/command-ref/meson.build

@@ -1,9 +1,3 @@
-xp_features_json = custom_target(
-  command : [nix, '__dump-xp-features'],
-  capture : true,
-  output : 'xp-features.json',
-)
-
 experimental_features_shortlist_md = custom_target(
   command : nix_eval_for_docs + [
     '--expr',
@@ -11,7 +5,7 @@ experimental_features_shortlist_md = custom_target(
   ],
   input : [
     '../../generate-features-shortlist.nix',
-    xp_features_json,
+    nix_exp_features_json,
   ],
   capture : true,
   output : 'experimental-features-shortlist.md',

doc/manual/src/contributing/meson.build

@@ -8,7 +8,7 @@ experimental_feature_descriptions_md = custom_target(
   ],
   input : [
     '../../generate-features.nix',
-    xp_features_json,
+    nix_exp_features_json,
   ],
   capture : true,
   output : 'experimental-feature-descriptions.md',