Detect whether __sync_moo is usable, don't just fail if it's not.

May not be perfect, but this unhides a few ports on mips64* and hppa.

ok landry@ sthen@

devel/json-c/Makefile

@@ -1,7 +1,4 @@
-# $OpenBSD: Makefile,v 1.12 2015/08/24 18:35:39 jca Exp $
-
-BROKEN-hppa=		undefined reference to __sync_val_compare_and_swap_4
-BROKEN-mips64=		undefined reference to __sync_val_compare_and_swap_4
+# $OpenBSD: Makefile,v 1.13 2015/08/25 11:37:02 jca Exp $
 
 COMMENT=		JSON implementation in C
 
@@ -18,7 +15,8 @@ PERMIT_PACKAGE_CDROM=	Yes
 
 MASTER_SITES =		https://s3.amazonaws.com/json-c_releases/releases/
 
-CONFIGURE_STYLE=	gnu
+CONFIGURE_STYLE=	autoconf autoheader
+AUTOCONF_VERSION=	2.69
 
 # not enabled by default at present, but we want to make sure we
 # don't use it if it's later enabled as it disables using random(4).

devel/json-c/patches/patch-configure_ac

@@ -0,0 +1,25 @@
+$OpenBSD: patch-configure_ac,v 1.1 2015/08/25 11:37:02 jca Exp $
+--- configure.ac.orig	Mon Aug 24 20:07:25 2015
++++ configure.ac	Mon Aug 24 20:06:41 2015
+@@ -66,6 +66,21 @@ int main(int c,char* v) {return 0;}
+    AC_MSG_RESULT(no)
+ ])
+ 
++AC_MSG_CHECKING([if compiler supports __sync_val_compare_and_swap with int objects])
++AC_LINK_IFELSE([AC_LANG_SOURCE([[
++int
++main(void) {
++    int r = 0;
++    __sync_val_compare_and_swap(&r, 0, 1);
++    return 0;
++}
++]])], [
++    AC_DEFINE(HAS___SYNC_VAL_COMPARE_AND_SWAP_INT, 1, [Define if compiler supports __sync_val_compare_and_swap.])
++    AC_MSG_RESULT(yes)
++], [
++   AC_MSG_RESULT(no)
++])
++
+ AC_LANG_POP([C])
+ 
+ AM_PROG_LIBTOOL

devel/json-c/patches/patch-linkhash_c

@@ -0,0 +1,25 @@
+$OpenBSD: patch-linkhash_c,v 1.1 2015/08/25 11:37:02 jca Exp $
+--- linkhash.c.orig	Fri Apr 11 02:41:08 2014
++++ linkhash.c	Mon Aug 24 20:41:34 2015
+@@ -23,6 +23,7 @@
+ 
+ #include "random_seed.h"
+ #include "linkhash.h"
++#include "config.h"
+ 
+ void lh_abort(const char *msg, ...)
+ {
+@@ -405,12 +406,11 @@ unsigned long lh_char_hash(const void *k)
+ 		int seed;
+ 		/* we can't use -1 as it is the unitialized sentinel */
+ 		while ((seed = json_c_get_random_seed()) == -1);
+-#if defined __GNUC__
++#if defined HAS___SYNC_VAL_COMPARE_AND_SWAP_INT
+ 		__sync_val_compare_and_swap(&random_seed, -1, seed);
+ #elif defined _MSC_VER
+ 		InterlockedCompareExchange(&random_seed, seed, -1);
+ #else
+-#warning "racy random seed initializtion if used by multiple threads"
+ 		random_seed = seed; /* potentially racy */
+ #endif
+ 	}