Teach perf script to print user regs.

  % perf record --user-regs=ip,sp ...
  % perf script -F ip,sym,uregs
  ...
   ffffffff9e060c24 native_write_msr ABI:2    SP:0x7ffd0ea06c38    IP:0x7fe77f55b637
   ffffffff9e060c24 native_write_msr ABI:2    SP:0x7ffd0ea06c38    IP:0x7fe77f55b637
   ffffffff9e060c24 native_write_msr ABI:2    SP:0x7ffd0ea06c38    IP:0x7fe77f55b637
   ffffffff9e060c24 native_write_msr ABI:2    SP:0x7ffd0ea06c38    IP:0x7fe77f55b637
   ffffffff9e00cc12 intel_pmu_handle_irq ABI:2    SP:0x7ffd0ea06c38    IP:0x7fe77f55b637

v2: Rebased on top of phys-addr patches
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/20170905184057.26135-1-andi@firstfloor.org
[ Use PRIu64 for regs->abi in print_sample_uregs() ]
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>