cmake: Fix build of xcb platform plugin when vulkan is available

Change-Id: I79760aa0cb08752cfc20aabc1a890f60c91c9dfd
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/platformsupport/CMakeLists.txt

@@ -19,6 +19,10 @@ if(QT_FEATURE_accessibility)
     endif()
 endif()
 
+if(QT_FEATURE_vulkan)
+    add_subdirectory(vkconvenience)
+endif()
+
 if(APPLE)
     add_subdirectory(clipboard)
     add_subdirectory(graphics)

src/platformsupport/vkconvenience/CMakeLists.txt

@@ -0,0 +1,16 @@
+# Generated from vkconvenience.pro.
+
+#####################################################################
+## VulkanSupport Module:
+#####################################################################
+
+add_qt_module(VulkanSupport
+    STATIC
+    SOURCES
+        qbasicvulkanplatforminstance.cpp qbasicvulkanplatforminstance_p.h
+    DEFINES
+        QT_NO_CAST_FROM_ASCII
+    LIBRARIES
+        Qt::CorePrivate
+        Qt::GuiPrivate
+)

src/plugins/platforms/xcb/CMakeLists.txt

@@ -75,7 +75,7 @@ extend_target(XcbQpa CONDITION TARGET Qt::LinuxAccessibilitySupportPrivate
 
 extend_target(XcbQpa CONDITION QT_FEATURE_vulkan
     LIBRARIES
-        vulkan_supportPrivate
+        VulkanSupportPrivate
 )
 
 extend_target(XcbQpa CONDITION QT_FEATURE_draganddrop