xulrunner192: fix build on netbsd-current

This package uses a cdefs.h that originated out of BSD so redefines a lot
of macros normally in BSD's cdefs.h. avoid redefining if those macros
already exist.

Adjust GCC version check to match intention, it was GCC < 2.5 without
__attribute__, not every GCC with a minor below 5!

Patch from Chavdar Ivanov on pkgsrc-users, adjusted to be more conservative
by myself (it's likely some operating systems do need __BEGIN_DECLS!)

PKGREVISION->38 out of paranoia

devel/xulrunner192/Makefile

@@ -1,8 +1,8 @@
-# $NetBSD: Makefile,v 1.53 2017/04/22 21:03:34 adam Exp $
+# $NetBSD: Makefile,v 1.54 2017/08/05 09:39:01 maya Exp $
 
 .include "dist.mk"
 PKGNAME=	xulrunner192-${MOZ_BRANCH}${MOZ_BRANCH_MINOR}
-PKGREVISION=	37
+PKGREVISION=	38
 CATEGORIES=	devel www
 
 MAINTAINER=	pkgsrc-users@NetBSD.org

devel/xulrunner192/distinfo

@@ -1,4 +1,4 @@
-$NetBSD: distinfo,v 1.23 2016/09/16 11:42:24 jperkin Exp $
+$NetBSD: distinfo,v 1.24 2017/08/05 09:39:01 maya Exp $
 
 SHA1 (firefox-3.6.28.source.tar.bz2) = adeaa9bdd367878c5b522766e681798178e31577
 RMD160 (firefox-3.6.28.source.tar.bz2) = 87cfca8e3f1df30e06eccffbf994825904eeedbc
@@ -40,6 +40,7 @@ SHA1 (patch-config_milestone.pl) = 11252595ce322f6f3307ec6597ac4b9eb71bbf75
 SHA1 (patch-config_system-headers) = f0e83260d7fff51973ba1df7fd1eac2ad5edb294
 SHA1 (patch-content_svg_content_src_nsSVGFilters.cpp) = ab83b19616148054046f5b2befdd1c447e27d485
 SHA1 (patch-content_svg_content_src_nsSVGFilters.h) = d6a7b2616a450a182e227d917203b7369dbf184e
+SHA1 (patch-dbm_include_cdefs.h) = ee6ab75552ccd97e6ea901ff3e3081f9b7fa235a
 SHA1 (patch-dom_src_threads_nsDOMWorkerEvents.cpp) = 2e29c52ddefa76a7ce28307d6dc8c0a87d8cecc2
 SHA1 (patch-dom_src_threads_nsDOMWorkerEvents.h) = ab131c359b0a354615381ba4991b7f2d9d4cb723
 SHA1 (patch-embedding_browser_gtk_src_EmbedPrivate.cpp) = a0ec26c6ca751e51586498e33b4f51b63799e3d2

devel/xulrunner192/patches/patch-dbm_include_cdefs.h

@@ -0,0 +1,33 @@
+$NetBSD: patch-dbm_include_cdefs.h,v 1.1 2017/08/05 09:39:01 maya Exp $
+
+Don't redefine __BEGIN_DECLS
+Match GCC minimum version check to comment (don't spuriously apply to modern
+compilers)
+
+--- dbm/include/cdefs.h.orig	2012-03-06 14:45:25.000000000 +0000
++++ dbm/include/cdefs.h
+@@ -38,6 +38,7 @@
+ #ifndef	_CDEFS_H_
+ #define	_CDEFS_H_
+ 
++#ifndef __BEGIN_DECLS
+ #if defined(__cplusplus)
+ #define	__BEGIN_DECLS	extern "C" {
+ #define	__END_DECLS	}
+@@ -45,6 +46,7 @@
+ #define	__BEGIN_DECLS
+ #define	__END_DECLS
+ #endif
++#endif
+ 
+ /*
+  * The __CONCAT macro is used to concatenate parts of symbol names, e.g.
+@@ -109,7 +111,7 @@
+  * these work for GNU C++ (modulo a slight glitch in the C++ grammar
+  * in the distribution version of 2.5.5).
+  */
+-#if !defined(__GNUC__) || __GNUC__ < 2 || __GNUC_MINOR__ < 5
++#if !defined(__GNUC__) || (__GNUC__ < 2 && __GNUC_MINOR__ < 5)
+ #define	__attribute__(x)	/* delete __attribute__ if non-gcc or gcc1 */
+ #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
+ #define	__dead		__volatile