cmake : Do not install tools on iOS targets (#15903)

tools/mtmd/CMakeLists.txt

@@ -55,7 +55,7 @@ add_executable(llama-qwen2vl-cli  deprecation-warning.cpp)
 set(TARGET llama-mtmd-cli)
 add_executable         (${TARGET} mtmd-cli.cpp)
 set_target_properties  (${TARGET} PROPERTIES OUTPUT_NAME llama-mtmd-cli)
-if(NOT CMAKE_SYSTEM_NAME STREQUAL "iOS")
+if(LLAMA_TOOLS_INSTALL)
     install(TARGETS ${TARGET} RUNTIME)
 endif()
 target_link_libraries  (${TARGET} PRIVATE common mtmd Threads::Threads)