[gimp] data: fix more xmllint validation.

[Jehan <jehanp src gnome org>]

commit 27303619286e9d5694b1cff9523a671c334192e2
Author: Jehan <jehan girinstud io>
Date:   Fri Jun 18 15:46:41 2021 +0200

    data: fix more xmllint validation.
    
    Similarly to the previous commit, the tips and tags validation was never
    happening as it was implemented as a custom top-level meson target. It
    was not run during a normal build. Now it is.

 data/tags/meson.build | 7 +++++--
 data/tips/meson.build | 7 +++++--
 2 files changed, 10 insertions(+), 4 deletions(-)
---
diff --git a/data/tags/meson.build b/data/tags/meson.build
index ea57a16c16..464b87121f 100644
--- a/data/tags/meson.build
+++ b/data/tags/meson.build
@@ -19,12 +19,15 @@ gimp_tags_default = custom_target(xmlfilename,
 )
 
 if xmllint.found()
-  run_target('validate-tags',
+  custom_target('validate-tags',
     command: [
       xmllint,
-      '--noout',
+      '--output', '@OUTPUT@',
       '--path', meson.current_source_dir(),
       '--valid', gimp_tags_default,
     ],
+    output: [ 'validate-tags-output.xml' ],
+    build_by_default: true,
+    install: false
   )
 endif
diff --git a/data/tips/meson.build b/data/tips/meson.build
index 526a70b36e..490913f9cd 100644
--- a/data/tips/meson.build
+++ b/data/tips/meson.build
@@ -32,12 +32,15 @@ fortunes_tips = custom_target('fortunes-tips',
 )
 
 if xmllint.found()
-  run_target('validate-tips',
+  custom_target('validate-tips',
     command: [
       xmllint,
-      '--noout',
+      '--output', '@OUTPUT@',
       '--path', meson.current_source_dir(),
       '--valid', gimp_tips,
     ],
+    output: [ 'validate-tips-output.xml' ],
+    build_by_default: true,
+    install: false
   )
 endif