GNU/MIT Scheme: Attempt to fix Cygwin builds.

svn path=/nixpkgs/trunk/; revision=21295

pkgs/development/compilers/mit-scheme/default.nix

@@ -33,6 +33,9 @@ stdenv.mkDerivation {
 
   buildInputs = [ gnum4 ];
 
+  patches =
+    stdenv.lib.optional (stdenv.system == "i686-cygwin") ./ucontext-cygwin.patch;
+
   # XXX: The `check' target doesn't exist.
   doCheck = false;
 

pkgs/development/compilers/mit-scheme/ucontext-cygwin.patch

@@ -0,0 +1,13 @@
+Make `ucontext_t' definition visible on Cygwin.  See
+<http://thread.gmane.org/gmane.lisp.scheme.mit-scheme.devel/489>.
+
+--- mit-scheme-9.0.1/src/microcode/uxtrap.h	2010-02-09 01:09:53.000000000 +0100
++++ mit-scheme-9.0.1/src/microcode/uxtrap.h	2010-04-24 17:55:01.000000000 +0200
+@@ -27,6 +27,7 @@ USA.
+ #define SCM_UXTRAP_H
+ 
+ #include "os.h"
++#include <ucontext.h>
+ 
+ /* Machine/OS-dependent section (long) */
+