meson: Always use the / operator to join paths

This is the preferred way to do it, but there were a few
instances in which some of the path components had embedded
slashes instead.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

docs/internals/meson.build

@@ -12,7 +12,7 @@ html_xslt_gen = []
 foreach name : internals_in_files
   html_xslt_gen += {
     'name': name,
-    'source': 'docs/internals' / name + '.html.in',
+    'source': 'docs' / 'internals' / name + '.html.in',
   }
 endforeach