LN include/sys/vm86.h
  GEN include/bits/sysnum.h
<stdin>:1:24: fatal error: asm/unistd.h: No such file or directory
compilation terminated.
<stdin>:1:24: fatal error: asm/unistd.h: No such file or directory
compilation terminated.
ERROR: Could not generate syscalls.
Make sure that you have proper kernel headers.
Your .config in KERNEL_HEADERS="" was set to:
/usr/src/linux-headers-2.6.38-13-generic-pae/
make: *** [include/bits/sysnum.h] Error 1