The cpu_set_t type can only cope with NR_CPUS <= 1024, beyond this
it is neccessary to use alternate CPU_SET maps with a dynamically
allocated CPU map

* src/util/processinfo.c: Support new unlimited size CPU set type

* src/Makefile.am: Add processinfo.h/processinfo.c
* src/util/processinfo.c, src/util/processinfo.h: Module providing
  APIs for getting/setting process CPU affinity
* src/qemu/qemu_driver.c: Switch over to new APIs for schedular
  affinity
* src/libvirt_private.syms: Export virProcessInfoSetAffinity
  and virProcessInfoGetAffinity to internal drivers