Include stdarg.h in src/cppstring.cpp to fix build with GCC-based

architectures:

  /usr/local/include/gtkmm-2.0/glibmm/thread.h: In function 'void Glib::thread_init(GThreadFunctions*)':

Also add USES=dos2unix (to fix patching cppstring.cpp) gnome.

PR:		237040
Submitted by:	Piotr Kubaj

x11/decurs/Makefile

@@ -17,7 +17,8 @@ USE_GITHUB=	yes
 GH_ACCOUNT=	danfe
 GH_TAGNAME=	10c5691
 
-USES=		pkgconfig
+USES=		compiler:c++11-lang dos2unix gnome pkgconfig
+DOS2UNIX_FILES=	src/cppstring.cc
 GNU_CONFIGURE=	yes
 USE_XORG=	x11
 USE_GNOME=	gtk20

x11/decurs/files/patch-src_cppstring.cc

@@ -0,0 +1,10 @@
+--- src/cppstring.cc.orig	2019-04-05 11:08:03 UTC
++++ src/cppstring.cc
+@@ -4,6 +4,7 @@
+ #include "cppstring.hh"
+ #include "idefs.h"
+ #include <iostream>
++#include <stdarg.h>
+ // #include <except.h>
+ #define DEF_BUFFER_SIZE     512
+ #define CPPSTRING_ERROR(obj,msg,retval) {obj<<"*** ERROR *** : "<<msg<<std::endl;return retval;}