Fix Qt 6.7.1 cmake configure error

Qt 6.7.1 Web Assembly does not have support for designer package
So we disable building the designer plugin when building for Web Assembly

designer/CMakeLists.txt

@@ -1,36 +1,41 @@
-find_package(QT NAMES Qt6 REQUIRED COMPONENTS Core Widgets UiPlugin Gui Designer)
-find_package(Qt6 REQUIRED COMPONENTS Core Widgets UiPlugin Gui Designer)
+if(EMSCRIPTEN)
+    # WebAssembly specific code
+else()
+    find_package(QT NAMES Qt6 REQUIRED COMPONENTS Core Widgets UiPlugin Gui Designer)
+    find_package(Qt6 REQUIRED COMPONENTS Core Widgets UiPlugin Gui Designer)
 
-qt_add_plugin(qwt_designer)
+    qt_add_plugin(qwt_designer)
 
-target_include_directories(qwt_designer
-  PRIVATE
-  ../src/
-  ${CMAKE_CURRENT_LIST_DIR}/
-#  ${PROJECT_BINARY_DIR}/
-)
+    target_include_directories(qwt_designer
+      PRIVATE
+      ../src/
+      ${CMAKE_CURRENT_LIST_DIR}/
+    #  ${PROJECT_BINARY_DIR}/
+    )
 
-target_compile_definitions(qwt_designer
-    PRIVATE
-    "QWT_MOC_INCLUDE"
-)
-add_definitions(-DQT_PLUGIN)
-add_definitions(-DQT_NO_DEBUG)
-add_definitions(-DQT_SHARED)
-add_definitions(-DQDESIGNER_EXPORT_WIDGETS)
+    target_compile_definitions(qwt_designer
+        PRIVATE
+        "QWT_MOC_INCLUDE"
+    )
+    add_definitions(-DQT_PLUGIN)
+    add_definitions(-DQT_NO_DEBUG)
+    add_definitions(-DQT_SHARED)
+    add_definitions(-DQDESIGNER_EXPORT_WIDGETS)
 
-target_sources(qwt_designer
-  PRIVATE
-  qwt_designer_plugin.cpp
-  qwt_designer_plugin.qrc
-)
+    target_sources(qwt_designer
+      PRIVATE
+      qwt_designer_plugin.cpp
+      qwt_designer_plugin.qrc
+    )
 
-target_link_libraries(qwt_designer
-    PRIVATE
-        Qt6::Core
-        Qt6::Gui
-        Qt6::UiPlugin
-        Qt6::Widgets
-        Qt6::Designer
-        qwt
-)
+    target_link_libraries(qwt_designer
+        PRIVATE
+            Qt6::Core
+            Qt6::Gui
+            Qt6::UiPlugin
+            Qt6::Widgets
+            Qt6::Designer
+            qwt
+    )
+
+endif()