$OpenBSD: patch-configure_ac,v 1.5 2013/01/22 14:30:46 sthen Exp $
--- configure.ac.orig	Wed Jan  9 01:42:47 2013
+++ configure.ac	Tue Jan 22 12:58:39 2013
@@ -566,6 +566,16 @@ for module in $squid_disk_module_candidates none; do
               fi
             fi
             ;;
+          openbsd)
+            if test `echo "$squid_host_os_version" | tr -d .` -lt 52 ; then
+                AC_MSG_NOTICE(pthread library requires OpenBSD 5.2 or later)
+                squid_opt_use_diskthreads="no"
+            else
+              SQUID_CFLAGS="$SQUID_CFLAGS -D_REENTRANT"
+              SQUID_CXXFLAGS="$SQUID_CXXFLAGS -D_REENTRANT"
+              LDFLAGS="$LDFLAGS -lpthread"
+            fi
+            ;;
           solaris)
             if test "x$GCC" = "xyes" ; then
               SQUID_CFLAGS="$SQUID_CFLAGS -D_REENTRANT -pthreads"
@@ -3112,9 +3122,16 @@ if test "x$squid_host_os" = "xmingw" ; then
   ac_cv_func_statfs='yes'
 fi
 
+dnl Some systems (mostly BSDs) require -lexecinfo for backtrace_symbols_fd()
+AC_CHECK_LIB(execinfo,backtrace_symbols_fd,[BACKTRACE_LIB="-lexecinfo"])
+oLIBS=$LIBS
+LIBS="$BACKTRACE_LIB"
+AC_CHECK_FUNCS(backtrace_symbols_fd)
+LIBS=$oLIBS
+AC_SUBST(BACKTRACE_LIB)
+
 dnl Check for library functions
 AC_CHECK_FUNCS(\
-	backtrace_symbols_fd \
 	bcopy \
 	bswap_16 \
 	bswap_32 \