bug#57742: [PATCH core-updates] build: qt-utils: Add prefix when wrapping QT_PLUGIN_PATH variable.

[Antero Mejr]

This allows extension of QT_PLUGIN_PATH.
QT programs will now work under Wayland when qt-wayland is installed.

* guix/build/qt-utils.scm (variables-for-wrapping)[QT_PLUGIN_PATH]: Add prefix
value to 'wrap-program' procedure call for QT_PLUGIN_PATH variable.
---
Tested using Wayland and X (via XWayland), using plugin paths for QT5, QT6, or
both. In all cases, QT selects the correct plugin if it's present anywhere in
QT_PLUGIN_PATH.

 guix/build/qt-utils.scm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/guix/build/qt-utils.scm b/guix/build/qt-utils.scm
index 2e47f1bc02..b503659521 100644
--- a/guix/build/qt-utils.scm
+++ b/guix/build/qt-utils.scm
@@ -89,7 +89,7 @@ (define exists? (match file-type
     '("XDG_CONFIG_DIRS" suffix directory "/etc/xdg")
     ;; We wrap exactly to avoid potentially mixing Qt5/Qt6 components, which
     ;; would cause warnings, perhaps problems.
-    `("QT_PLUGIN_PATH" = directory
+    `("QT_PLUGIN_PATH" prefix directory
       ,(format #f "/lib/qt~a/plugins" qt-major-version))
     `("QML2_IMPORT_PATH" = directory
       ,(format #f "/lib/qt~a/qml" qt-major-version))
-- 
2.38.1