meson: only install broadway man pages if it's enabled

.gitlab-ci/test-msys2-meson.sh

@@ -41,6 +41,7 @@ ccache --show-stats
 
 meson \
     -Dman-pages=true \
+    -Dbroadway-backend=true \
     _build
 
 ninja -C _build

docs/reference/gtk/meson.build

@@ -514,11 +514,14 @@ if get_option('man-pages') and xsltproc.found()
     [ 'gtk3-demo-application', '1', ],
     [ 'gtk3-widget-factory', '1', ],
     [ 'gtk3-icon-browser', '1', ],
-    [ 'broadwayd', '1', ],
     [ 'gtk-builder-tool', '1', ],
     [ 'gtk-query-settings', '1', ],
   ]
 
+  if broadway_enabled
+    man_files += [[ 'broadwayd', '1', ]]
+  endif
+
   foreach man: man_files
     man_name = man.get(0)
     man_section = man.get(1, '1')