$NetBSD: patch-configure,v 1.3 2022/08/25 21:46:53 thor Exp $

Portability fix.
Make it use weak symbols with Clang.

--- configure.orig	2021-12-16 17:26:22.000000000 +0000
+++ configure
@@ -30608,7 +30608,9 @@ else
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
+#ifndef __clang__
 extern int PFoo(int);
+#endif
 #pragma weak PFoo = Foo
 int Foo(int a) { return a; }
 
@@ -57640,7 +57642,7 @@ esac
 # - enable-thread-cs=per-vci
 #
 if test "$enable_ch4_mt" != "direct"; then
-    if test "${with_zm_prefix}" == "no" -o "${with_zm_prefix}" == "none" -o "${enable_izem_queue}" != "yes" ; then
+    if test "${with_zm_prefix}" = "no" -o "${with_zm_prefix}" = "none" -o "${enable_izem_queue}" != "yes" ; then
         as_fn_error $? "Multi-threading model \`${enable_ch4_mt}\` requires izem queue. Set \`--enable-izem={queue|all} --with-zm-prefix\` and retry." "$LINENO" 5
     elif test "${enable_thread_cs}" != "per-vci" -a "${enable_thread_cs}" != "per_vci"; then
         as_fn_error $? "Multi-threading model \`${enable_ch4_mt}\` requires \`--enable-thread-cs=per-vci\`." "$LINENO" 5