[3.14] gh-150443: Exclude explicit dup3 and pipe2 checks on iOS builds. (GH-150444) (#150447)

Exclude explicit dup3 and pipe2 checks on iOS builds.
(cherry picked from commit 629da5c)

Author: freakboy3742

configure

@@ -5264,7 +5264,7 @@ fi
 # checks for library functions
 AC_CHECK_FUNCS([ \
   accept4 alarm bind_textdomain_codeset chmod chown clock closefrom close_range confstr \
-  copy_file_range ctermid dladdr dup dup3 execv explicit_bzero explicit_memset \
+  copy_file_range ctermid dladdr dup execv explicit_bzero explicit_memset \
   faccessat fchmod fchmodat fchown fchownat fdopendir fdwalk fexecve \
   fork fork1 fpathconf fstatat ftime ftruncate futimens futimes futimesat \
   gai_strerror getegid geteuid getgid getgrent getgrgid getgrgid_r \
@@ -5274,7 +5274,7 @@ AC_CHECK_FUNCS([ \
   getspnam getuid getwd grantpt if_nameindex initgroups kill killpg lchown linkat \
   lockf lstat lutimes madvise mbrtowc memrchr mkdirat mkfifo mkfifoat \
   mknod mknodat mktime mmap mremap nice openat opendir pathconf pause pipe \
-  pipe2 plock poll posix_fadvise posix_fallocate posix_openpt posix_spawn posix_spawnp \
+  plock poll posix_fadvise posix_fallocate posix_openpt posix_spawn posix_spawnp \
   posix_spawn_file_actions_addclosefrom_np \
   pread preadv preadv2 process_vm_readv \
   pthread_cond_timedwait_relative_np pthread_condattr_setclock pthread_init \
@@ -5305,7 +5305,7 @@ fi
 # header definition prevents usage - autoconf doesn't use the headers), or
 # raise an error if used at runtime. Force these symbols off.
 if test "$ac_sys_system" != "iOS" ; then
-  AC_CHECK_FUNCS([getentropy getgroups system])
+  AC_CHECK_FUNCS([dup3 getentropy getgroups pipe2 system])
 fi
 
 AC_CHECK_DECL([dirfd],