bpo-28762: Revert last commit (now using Android Unified Headers) (GH-4488)

diff --git a/configure b/configure
index 969e1d5..d026757 100755
--- a/configure
+++ b/configure
@@ -11147,7 +11147,7 @@
  getgrouplist getgroups getlogin getloadavg getpeername getpgid getpid \
  getpriority getresuid getresgid getpwent getspnam getspent getsid getwd \
  if_nameindex \
- initgroups kill killpg lchmod lchown linkat lstat lutimes mmap \
+ initgroups kill killpg lchmod lchown lockf linkat lstat lutimes mmap \
  memrchr mbrtowc mkdirat mkfifo \
  mkfifoat mknod mknodat mktime mremap nice openat pathconf pause pipe2 plock poll \
  posix_fallocate posix_fadvise pread \
@@ -12581,35 +12581,6 @@
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 
-# Issue #28762: lockf() is available on Android API level 24, but the F_LOCK
-# macro is not defined in android-ndk-r13.
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for lockf" >&5
-$as_echo_n "checking for lockf... " >&6; }
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <unistd.h>
-int
-main ()
-{
-lockf(0, F_LOCK, 0);
-  ;
-  return 0;
-}
-_ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
-
-$as_echo "#define HAVE_LOCKF 1" >>confdefs.h
-
-   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-
-fi
-rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext conftest.$ac_ext
-
 # On OSF/1 V5.1, getaddrinfo is available, but a define
 # for [no]getaddrinfo in netdb.h.
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for getaddrinfo" >&5