cmake:bugfix fix CMake LTO build block

it was wrong in https://github.com/apache/nuttx/pull/12423/files#r1618852245
EXTRA_FLAGS is useful in LTO for pass option tu lto linker

Signed-off-by: xuxin19 <xuxin19@xiaomi.com>

CMakeLists.txt

@@ -642,8 +642,8 @@ if(NOT CONFIG_ARCH_SIM)
 
   # TODO: nostart/nodefault not applicable to nuttx toolchain
   target_link_libraries(
-    nuttx PRIVATE -T${ldscript} -Wl,--start-group ${nuttx_libs}
-                  ${nuttx_extra_libs} -Wl,--end-group)
+    nuttx PRIVATE ${NUTTX_EXTRA_FLAGS} -T${ldscript} -Wl,--start-group
+                  ${nuttx_libs} ${nuttx_extra_libs} -Wl,--end-group)
 
   # generate binary outputs in different formats (.bin, .hex, etc)
   nuttx_generate_outputs(nuttx)

libs/libc/assert/CMakeLists.txt

@@ -24,7 +24,10 @@ if(CONFIG_STACK_CANARIES)
   list(APPEND SRCS lib_stackchk.c)
 endif()
 
-set_source_files_properties(lib_assert.c PROPERTIES COMPILE_FLAGS -fno-lto)
-set_source_files_properties(lib_stackchk.c PROPERTIES COMPILE_FLAGS -fno-lto)
-
+if(CONFIG_ARCH_TOOLCHAIN_GNU AND NOT CONFIG_LTO_NONE)
+  set_source_files_properties(lib_assert.c DIRECTORY .. PROPERTIES COMPILE_FLAGS
+                                                                   -fno-lto)
+  set_source_files_properties(lib_stackchk.c DIRECTORY ..
+                              PROPERTIES COMPILE_FLAGS -fno-lto)
+endif()
 target_sources(c PRIVATE ${SRCS})