[buoh] build: Fix deprecations

[Jan Tojnar <jtojnar src gnome org>]

commit 9db53156dab8f05169789ff84272b698b3fa4e62
Author: Jan Tojnar <jtojnar gmail com>
Date:   Mon Feb 21 16:12:15 2022 +0100

    build: Fix deprecations
    
    WARNING: Project targeting '>= 0.57.0' but tried to use feature deprecated since '0.56.0': 
meson.source_root. use meson.current_source_dir instead.
    WARNING: Project targeting '>= 0.57.0' but tried to use feature deprecated since '0.55.0': 
ExternalProgram.path. use ExternalProgram.full_path() instead

 data/meson.build | 2 +-
 meson.build      | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)
---
diff --git a/data/meson.build b/data/meson.build
index 274d48e..6a566f4 100644
--- a/data/meson.build
+++ b/data/meson.build
@@ -16,7 +16,7 @@ if gtk_builder_tool.found() and xsltproc.found()
       output: '@PLAINNAME@',
       command: [
         xsltproc,
-        join_paths(meson.source_root(), 'build-aux', 'ui-pre-validation.xsl'),
+        join_paths(meson.project_source_root(), 'build-aux', 'ui-pre-validation.xsl'),
         '@INPUT@',
       ],
       capture: true,
diff --git a/meson.build b/meson.build
index 30973ea..88f2907 100644
--- a/meson.build
+++ b/meson.build
@@ -10,8 +10,8 @@ project(
 
 gnome = import('gnome')
 i18n = import('i18n')
-data_dir = join_paths(meson.source_root(), 'data')
-po_dir = join_paths(meson.source_root(), 'po')
+data_dir = join_paths(meson.current_source_dir(), 'data')
+po_dir = join_paths(meson.current_source_dir(), 'po')
 
 prefix = get_option('prefix')
 bindir = join_paths(prefix, get_option('bindir'))
@@ -45,8 +45,8 @@ buoh_deps = [
 if appstream_util.found()
   meson.add_dist_script(
     python3,
-    join_paths(meson.source_root(), 'build-aux', 'dist-news.py'),
-    appstream_util.path(),
+    join_paths(meson.current_source_dir(), 'build-aux', 'dist-news.py'),
+    appstream_util.full_path(),
   )
 endif