meson: clean up unnecessary variables

The `manpage_target` variable isn't used at all, and the `manpage_path`
variable is only used in a single location. Remove the former variable
and inline the latter.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/meson.build

@@ -375,8 +375,7 @@ foreach manpage, category : manpages
       output: fs.stem(manpage) + '.xml',
     )
 
-    manpage_path = fs.stem(manpage) + '.' + category.to_string()
-    manpage_target = custom_target(
+    custom_target(
       command: [
         xmlto,
         '-m', '@INPUT0@',
@@ -392,7 +391,7 @@ foreach manpage, category : manpages
         'manpage-normal.xsl',
         'manpage-bold-literal.xsl',
       ],
-      output: manpage_path,
+      output: fs.stem(manpage) + '.' + category.to_string(),
       install: true,
       install_dir: get_option('mandir') / 'man' + category.to_string(),
     )