Add a meson flag to make cool URIs optional

The script `ensure-stable-doc-urls.py` relies on the Doxygen output files
names. These may change between Doxygen versions, although the Doxygen
developers intend stability.

Since the script is useful mainly for the online documentation of
xkbcommon, make the target `doc-cool-uris` optional.

meson.build

@@ -833,6 +833,7 @@ You can disable the documentation with -Denable-docs=false.''')
         install_dir: docdir,
         build_by_default: true,
     )
+    if get_option('enable-cool-uris')
         ensure_stable_urls = find_program('scripts'/'ensure-stable-doc-urls.py')
         custom_target(
             'doc-cool-uris',
@@ -847,6 +848,7 @@ You can disable the documentation with -Denable-docs=false.''')
             install: false,
             build_by_default: true,
         )
+    endif
 endif
 
 configure_file(output: 'config.h', configuration: configh_data)

meson_options.txt

@@ -61,6 +61,12 @@ option(
     value: true,
     description: 'Enable building the documentation',
 )
+option(
+    'enable-cool-uris',
+    type: 'boolean',
+    value: false,
+    description: 'Enable creating redirections to maintain stable documentation pages',
+)
 option(
     'enable-wayland',
     type: 'boolean',