CMake: Fix feature evaluation for feature defines

Passing -DFEATURE_developer_build=TRUE did not add the define
QT_BUILD_INTERNAL to src/corelib/global/qconfig.h like
-DFEATURE_developer_build=ON would.

This happened, because the feature evaluation in
qt_evaluate_feature_definition did a string comparison against "ON".

Normalize both sides of the string comparison, and thus support all
booly values for features.

Pick-to: 6.2
Fixes: QTBUG-95732
Change-Id: Ibf03579c05919b35219438361fc93676b7cca7cc
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

cmake/QtFeature.cmake

@@ -492,9 +492,14 @@ function(qt_evaluate_feature_definition key)
         set(expected OFF)
     endif()
 
+    set(actual OFF)
+    if(QT_FEATURE_${arg_FEATURE})
+        set(actual ON)
+    endif()
+
     set(msg "")
 
-    if(QT_FEATURE_${arg_FEATURE} STREQUAL expected)
+    if(actual STREQUAL expected)
         set(indent "")
         if(arg_PREREQUISITE)
             string(APPEND msg "#if ${arg_PREREQUISITE}\n")