ci: avoid building manpages on Fedora

It appears that xsltproc is not installed there. It is generally needed
for the docs build too, so as a crude CI heuristic, don't build anywhere
that docs are disabled.

contrib/scripts/nm-ci-run.sh

@@ -167,6 +167,7 @@ meson setup build \
     -D libpsl=false \
     -D vapi=false \
     -D introspection=$_WITH_DOCS \
+    -D man=$_WITH_DOCS \
     -D qt=false \
     -D crypto=$_WITH_CRYPTO \
     -D docs=$_WITH_DOCS \