cmake: use -fvisibility=default for "arch"

so that macos build can find "_sim_netdriver_setmacaddr" etc.

arch/sim/src/sim/CMakeLists.txt

@@ -241,6 +241,7 @@ target_sources(sim_head PUBLIC sim_head.c sim_doirq.c)
 
 target_include_directories(arch PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
 target_sources(arch PRIVATE ${SRCS})
+target_compile_options(arch PRIVATE -fvisibility=default)
 
 if(WIN32)
   set(HOSTDIR win)