Use TARGET_OBJECTS generator expression in CMake for core builds (maplibre#3484)

Author: louwers

platform/linux/linux.cmake

@@ -142,8 +142,8 @@ target_include_directories(
 include(${PROJECT_SOURCE_DIR}/vendor/nunicode.cmake)
 include(${PROJECT_SOURCE_DIR}/vendor/sqlite.cmake)
 
-if(NOT ${ICU_FOUND} OR "${ICU_VERSION}" VERSION_LESS 62.0)
-    message(STATUS "ICU not found or too old, using builtin.")
+if(NOT ${ICU_FOUND} OR "${ICU_VERSION}" VERSION_LESS 62.0 OR MLN_USE_BUILTIN_ICU)
+    message(STATUS "ICU not found, too old or MLN_USE_BUILTIN_ICU requestd, using builtin.")
 
     set(MLN_USE_BUILTIN_ICU TRUE)
     include(${PROJECT_SOURCE_DIR}/vendor/icu.cmake)
@@ -167,7 +167,7 @@ target_link_libraries(
         ${WEBP_LIBRARIES}
         $<$<NOT:$<BOOL:${MLN_USE_BUILTIN_ICU}>>:ICU::i18n>
         $<$<NOT:$<BOOL:${MLN_USE_BUILTIN_ICU}>>:ICU::uc>
-        $<$<BOOL:${MLN_USE_BUILTIN_ICU}>:mbgl-vendor-icu>
+        $<$<BOOL:${MLN_USE_BUILTIN_ICU}>:$<IF:$<BOOL:${MLN_CORE_INCLUDE_DEPS}>,$<TARGET_OBJECTS:mbgl-vendor-icu>,mbgl-vendor-icu>>
         PNG::PNG
         mbgl-vendor-nunicode
         mbgl-vendor-sqlite