docs: ensure HTML/images are built before running reference tests

The 'check-html-references' test will process the built HTML files,
so they must exist before it is run, along with any images that
they point to.

If using the older 'configure_file' command, no changes are needed
since that always gets executed at 'meson setup' time, rather than
at 'meson compile' time.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

docs/images/meson.build

@@ -18,7 +18,8 @@ foreach file : docs_image_files
   # This hack enables us to view the web pages
   # from within the uninstalled build tree
   if meson.version().version_compare('>=0.64.0')
-    fs.copyfile(file)
+    imgfile = fs.copyfile(file)
+    install_web_deps += imgfile
   else
     configure_file(input: file, output: file, copy: true)
   endif

docs/logos/meson.build

@@ -26,7 +26,8 @@ foreach file : docs_logo_files
   # This hack enables us to view the web pages
   # from within the uninstalled build tree
   if meson.version().version_compare('>=0.64.0')
-    fs.copyfile(file)
+    logofile = fs.copyfile(file)
+    install_web_deps += logofile
   else
     configure_file(input: file, output: file, copy: true)
   endif

docs/meson.build

@@ -360,6 +360,7 @@ if tests_enabled[0]
       '--webroot',
       meson.project_build_root() / 'docs'
     ],
+    depends: install_web_deps,
     env: runutf8,
     suite: 'script'
   )