Use -lldap_r by default.

diff -up php-7.4.0RC2/ext/ldap/config.m4.ldap_r php-7.4.0RC2/ext/ldap/config.m4
--- php-7.4.0RC2/ext/ldap/config.m4.ldap_r	2019-09-17 10:21:24.769200812 +0200
+++ php-7.4.0RC2/ext/ldap/config.m4	2019-09-17 10:21:30.658181771 +0200
@@ -68,7 +68,11 @@ if test "$PHP_LDAP" != "no"; then
   dnl -pc removal is a hack for clang
   MACHINE_INCLUDES=$($CC -dumpmachine | $SED 's/-pc//')
 
-  if test -f $LDAP_LIBDIR/liblber.a || test -f $LDAP_LIBDIR/liblber.$SHLIB_SUFFIX_NAME || test -f $LDAP_LIBDIR/$MACHINE_INCLUDES/liblber.a || test -f $LDAP_LIBDIR/$MACHINE_INCLUDES/liblber.$SHLIB_SUFFIX_NAME; then
+  if test -f $LDAP_LIBDIR/libldap_r.$SHLIB_SUFFIX_NAME; then
+    PHP_ADD_LIBRARY_WITH_PATH(lber, $LDAP_LIBDIR, LDAP_SHARED_LIBADD)
+    PHP_ADD_LIBRARY_WITH_PATH(ldap_r, $LDAP_LIBDIR, LDAP_SHARED_LIBADD)
+
+  elif test -f $LDAP_LIBDIR/liblber.a || test -f $LDAP_LIBDIR/liblber.$SHLIB_SUFFIX_NAME || test -f $LDAP_LIBDIR/$MACHINE_INCLUDES/liblber.a || test -f $LDAP_LIBDIR/$MACHINE_INCLUDES/liblber.$SHLIB_SUFFIX_NAME; then
     PHP_ADD_LIBRARY_WITH_PATH(lber, $LDAP_LIBDIR, LDAP_SHARED_LIBADD)
     PHP_ADD_LIBRARY_WITH_PATH(ldap, $LDAP_LIBDIR, LDAP_SHARED_LIBADD)