patch 8.2.1570: configure check for dirfd() does not work on HPUX

Problem:    Configure check for dirfd() does not work on HPUX. (Michael Osipov)
Solution:   Use AC_TRY_LINK instead of AC_TRY_COMPILE. (closes #6838)
diff --git a/src/configure.ac b/src/configure.ac
index a2683a6..6176dc9 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -4013,7 +4013,7 @@
 
 dnl check for dirfd()
 AC_MSG_CHECKING(for dirfd)
-AC_TRY_COMPILE(
+AC_TRY_LINK(
 [#include <sys/types.h>
 #include <dirent.h>],
 [DIR * dir=opendir("dirname"); dirfd(dir);],
@@ -4021,7 +4021,7 @@
 
 dnl check for flock()
 AC_MSG_CHECKING(for flock)
-AC_TRY_COMPILE(
+AC_TRY_LINK(
 [#include <sys/file.h>],
 [flock(10, LOCK_SH);],
 AC_MSG_RESULT(yes); AC_DEFINE(HAVE_FLOCK), AC_MSG_RESULT(not usable))