Installing Xen on Ubuntu: Error bits/predefs.h: No such file or directory

  This error cropped up when we were building Xen on a system running Ubuntu 12.04 Server:  
/usr/include/features.h:324:26: fatal error: bits/predefs.h: No such file or directory  
To get past this point, install gcc-multilib.  
sudo apt-get install gcc-multilib
  The required files are around 20MB and should allow you to get past that point of “make”.