Issue #28762: lockf() is available on Android API level 24, but the
F_LOCK macro is not defined in android-ndk-r13.
diff --git a/configure b/configure
index a05009a..e10510d 100755
--- a/configure
+++ b/configure
@@ -11198,7 +11198,7 @@
  futimens futimes gai_strerror getentropy \
  getgrouplist getgroups getlogin getloadavg getpeername getpgid getpid \
  getpriority getresuid getresgid getpwent getspnam getspent getsid getwd \
- initgroups kill killpg lchmod lchown lockf linkat lstat lutimes mmap \
+ initgroups kill killpg lchmod lchown 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 \
@@ -12690,6 +12690,35 @@
 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