rivet: fix runtime on darwin

pkgs/development/libraries/physics/rivet/darwin.patch

@@ -0,0 +1,33 @@
+diff --git a/include/Rivet/Tools/osdir.hh b/include/Rivet/Tools/osdir.hh
+index 05f06ca..59af7de 100644
+--- a/include/Rivet/Tools/osdir.hh
++++ b/include/Rivet/Tools/osdir.hh
+@@ -21,7 +21,7 @@
+ 
+ /// @cond OSDIR
+ 
+-#if defined(unix) || defined(__unix) || defined(__unix__)
++#if defined(unix) || defined(__unix) || defined(__unix__) || defined(__APPLE__)
+ #define OSLINK_OSDIR_POSIX
+ #elif defined(_WIN32)
+ #define OSLINK_OSDIR_WINDOWS
+@@ -32,18 +32,7 @@
+ #include <string>
+ 
+ #if defined(OSLINK_OSDIR_NOTSUPPORTED)
+-
+-namespace oslink
+-{
+-	class directory
+-	{
+-		public:
+-			directory(const std::string&)		{ }
+-			operator void*() const				{ return (void*)0; }
+-			std::string next()					{ return ""; }
+-	};
+-}
+-
++#error Platform misdetected or oslink is not implemented
+ #elif defined(OSLINK_OSDIR_POSIX)
+ 
+ #include <sys/types.h>

pkgs/development/libraries/physics/rivet/default.nix

@@ -13,6 +13,10 @@ stdenv.mkDerivation rec {
 
   pythonPath = []; # python wrapper support
 
+  patches = [
+    ./darwin.patch # configure relies on impure sw_vers to -Dunix
+  ];
+
   latex = texlive.combine { inherit (texlive)
     scheme-basic
     collection-pstricks