Set noexecstack CXX link flags for wamrc (#1303)

Set noexecstack CXX link flags for wamrc to avoid generating binary
with exec stack.

wamr-compiler/CMakeLists.txt

@@ -226,6 +226,7 @@ if (NOT MSVC)
 endif()
 if (NOT (MSVC OR CMAKE_C_COMPILER MATCHES ".*clang.*" OR CMAKE_C_COMPILER_ID MATCHES ".*Clang"))
   set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wl,-z,noexecstack,-z,relro,-z,now")
+  set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wl,-z,noexecstack,-z,relro,-z,now")
 endif()
 
 # We disable these flags by default to stay the same with wasm runtime