Qt4: Use generator expression in COMPILE_DEFINITIONS (#14692)

Commit 5bb53f6b (cmTarget: Deprecate COMPILE_DEFINITIONS_ properties
with a policy., 2013-12-30) deprecated the config-specific
COMPILE_DEFINITIONS_* properties in favour of using generator
expressions.

Set the directory property in UseQt4.cmake to match the
INTERFACE_COMPILE_DEFINITIONS on the Qt4::QtCore and Qt5::Core
IMPORTED targets.  Setting QT_NO_DEBUG is sufficient because qglobal.h
sets the corresponding QT_DEBUG definition if required.

Modules/UseQt4.cmake

@@ -22,13 +22,7 @@
 #  License text for the above reference.)
 
 add_definitions(${QT_DEFINITIONS})
-set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS_DEBUG QT_DEBUG)
-set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS_RELEASE QT_NO_DEBUG)
-set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS_RELWITHDEBINFO QT_NO_DEBUG)
-set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS_MINSIZEREL QT_NO_DEBUG)
-if(NOT CMAKE_CONFIGURATION_TYPES AND NOT CMAKE_BUILD_TYPE)
-  set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS QT_NO_DEBUG)
-endif()
+set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS $<$<NOT:$<CONFIG:Debug>>:QT_NO_DEBUG>)
 
 if(QT_INCLUDE_DIRS_NO_SYSTEM)
   include_directories(${QT_INCLUDE_DIR})