monosat, python3Packages.monosat: fix for non-x86

pkgs/applications/science/logic/monosat/default.nix

@@ -28,9 +28,18 @@ let
     })
   ];
 
+  # source behind __linux__ check assumes system is also x86 and
+  # tries to disable x86/x87-specific extended precision mode
+  # https://github.com/sambayless/monosat/issues/33
+  commonPostPatch = lib.optionalString (!(stdenv.isi686 || stdenv.isx86_64)) ''
+    substituteInPlace src/monosat/Main.cc \
+      --replace 'defined(__linux__)' '0'
+  '';
+
   core = stdenv.mkDerivation {
     name = "${pname}-${version}";
     inherit src patches;
+    postPatch = commonPostPatch;
     nativeBuildInputs = [ cmake ];
     buildInputs = [ zlib gmp jdk8 ];
 
@@ -66,7 +75,7 @@ let
 
     # After patching src, move to where the actually relevant source is. This could just be made
     # the sourceRoot if it weren't for the patch.
-    postPatch = ''
+    postPatch = commonPostPatch + ''
       cd src/monosat/api/python
     '' +
     # The relative paths here don't make sense for our Nix build