cmake: Add some symbols to the Emscripten preseed cache.

cmake/PreseedEmscriptenCache.cmake

@@ -175,5 +175,11 @@ if(EMSCRIPTEN)
     set(HAVE_MEMFD_CREATE                                ""    CACHE INTERNAL "Have symbol memfd_create")
     set(HAVE_POSIX_FALLOCATE                             "1"   CACHE INTERNAL "Have symbol posix_fallocate")
     set(HAVE_DLOPEN_IN_LIBC                              "1"   CACHE INTERNAL "Have symbol dlopen")
+    set(HAVE_FDATASYNC                                   "1"   CACHE INTERNAL "Have symbol fdatasync")
+    set(HAVE_GETHOSTNAME                                 "1"   CACHE INTERNAL "Have symbol gethostname")
+    set(HAVE_SIGTIMEDWAIT                                "1"   CACHE INTERNAL "Have symbol sigtimedwait")
+    set(HAVE_PPOLL                                       ""    CACHE INTERNAL "Have symbol ppoll")
+    set(HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR           ""    CACHE INTERNAL "Have symbol posix_spawn_file_actions_addchdir")
+    set(HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR_NP        "1"   CACHE INTERNAL "Have symbol posix_spawn_file_actions_addchdir_np")
   endfunction()
 endif()