Skip qtwebengine for -no-gui build

Fixes: QTBUG-75465
Change-Id: Iaf8c75d60d00dac3079fcb3f7108e1c3e5ea5245
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Michael Brüning <michael.bruning@qt.io>

mkspecs/features/configure.prf

@@ -4,6 +4,10 @@ load(functions)
 load(platform)
 
 defineTest(runConfigure) {
+    !qtHaveModule(gui) {
+        skipBuild("QtWebEngine requires QtGui.")
+        return(false)
+    }
 
     !exists(src/3rdparty/chromium) {
         skipBuild("Submodule qtwebengine-chromium does not exist. Run 'git submodule update --init'.")