Use QPlatformInputContextFactoryInterface_iid instead of interface name.

An API version number was added in
qtbase/c2e0c126d8be8782201b2e4b5e47d9abe7a64df0 to prevent crashes
when changing QPA APIs. Using the macro will result in the correct
name being used depending on Qt version.

Task-number: QTBUG-46009
Change-Id: I0e88cc8aef790c9c4bac90425db95d6203243444
Reviewed-by: Jarkko Koivikko <jarkko.koivikko@code-q.fi>

src/virtualkeyboard/plugin.h

@@ -27,7 +27,7 @@
 class PlatformInputContextPlugin : public QPlatformInputContextPlugin
 {
     Q_OBJECT
-    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QPlatformInputContextFactoryInterface" FILE "qtvirtualkeyboard.json")
+    Q_PLUGIN_METADATA(IID QPlatformInputContextFactoryInterface_iid FILE "qtvirtualkeyboard.json")
 
 public:
     QStringList keys() const;