boost: disable system Python.framework detection

There doesn't seem to be a --without-python flag and since the system
framework is always available the build tries to enable python support
while we have it disabled by default and explicitly don't pass in the
python headers.

pkgs/development/libraries/boost/generic.nix

@@ -87,11 +87,13 @@ stdenv.mkDerivation {
   inherit src;
 
   patchFlags = optionalString (hostPlatform.libc == "msvcrt") "-p0";
-  patches = patches ++ optional (hostPlatform.libc == "msvcrt") (fetchurl {
-    url = "https://svn.boost.org/trac/boost/raw-attachment/tickaet/7262/"
-        + "boost-mingw.patch";
-    sha256 = "0s32kwll66k50w6r5np1y5g907b7lcpsjhfgr7rsw7q5syhzddyj";
-  });
+  patches = patches
+    ++ optional stdenv.isDarwin ./darwin-no-system-python.patch
+    ++ optional (hostPlatform.libc == "msvcrt") (fetchurl {
+      url = "https://svn.boost.org/trac/boost/raw-attachment/tickaet/7262/"
+          + "boost-mingw.patch";
+      sha256 = "0s32kwll66k50w6r5np1y5g907b7lcpsjhfgr7rsw7q5syhzddyj";
+    });
 
   meta = {
     homepage = http://boost.org/;