$NetBSD$

Use PTHREAD_LDFLAGS variable instead of "-lpthread".

--- configure.orig	2021-09-03 17:06:13.000000000 +0000
+++ configure
@@ -18363,7 +18363,7 @@ if ${ac_cv_lib_pthread_pthread_exit+:} f
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lpthread  $LIBS"
+LIBS="${PTHREAD_LDFLAGS}  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -18398,7 +18398,7 @@ if test "x$ac_cv_lib_pthread_pthread_exi
 #define HAVE_LIBPTHREAD 1
 _ACEOF
 
-  LIBS="-lpthread $LIBS"
+  LIBS="${PTHREAD_LDFLAGS} $LIBS"
 
 fi