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
@@ -71,7 +71,11 @@
   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])