The wrapper features.h gets pulled in by system headers causing thigns to
break. We work around it by simply not wrap features.h

--- a/config/system-headers.orig
+++ b/config/system-headers
@@ -422,7 +422,6 @@
 extras.h
 fabdef.h
 fcntl.h
-features.h
 fibdef.h
 File.h
 filehdr.h