cpp: Fix cmake property mapping

Fix the mapping between a projects CMAKE_BUILD_TYPE and the build type
of the imported Slint library.

Fixes #1027

api/cpp/cmake/SlintConfig.cmake.in

@@ -13,6 +13,12 @@ endif()
 
 add_library(slint-cpp-shared SHARED IMPORTED)
 set_target_properties(slint-cpp-shared PROPERTIES @SLINT_LIB_PROPERTIES@)
+foreach(build_type Release RelWithDebInfo MinSizeRel Debug)
+  string(TOUPPER "${build_type}" config_name)
+  if(NOT("@CMAKE_BUILD_TYPE@" STREQUAL build_type))
+    set_target_properties(slint-cpp-shared PROPERTIES MAP_IMPORTED_CONFIG_${config_name} @CMAKE_BUILD_TYPE@)
+  endif()
+endforeach()
 
 add_executable(Slint::slint-compiler IMPORTED GLOBAL)
 set_target_properties(Slint::slint-compiler PROPERTIES IMPORTED_LOCATION "${_IMPORT_PREFIX}/@CMAKE_INSTALL_BINDIR@/slint-compiler${CMAKE_EXECUTABLE_SUFFIX}")