perf script: Add output of IPC ratio

Add field 'ipc' to display instructions-per-cycle.

Example:

 perf record -e intel_pt/cyc/u ls
 perf script --insn-trace --xed -F+ipc,-dso,-cpu,-tid

 ls  2670177.697113434:  7f0dfdbcd090 _start+0x0      mov %rsp, %rdi   IPC: 0.00 (1/877)
 ls  2670177.697113434:  7f0dfdbcd093 _start+0x3      callq  0x7f0dfdbce030
 ls  2670177.697113434:  7f0dfdbce030 _dl_start+0x0   pushq  %rbp
 ls  2670177.697113434:  7f0dfdbce031 _dl_start+0x1   mov %rsp, %rbp
 ls  2670177.697113434:  7f0dfdbce034 _dl_start+0x4   pushq  %r15
 ls  2670177.697113434:  7f0dfdbce036 _dl_start+0x6   pushq  %r14
 ls  2670177.697113434:  7f0dfdbce038 _dl_start+0x8   pushq  %r13
 ls  2670177.697113434:  7f0dfdbce03a _dl_start+0xa   pushq  %r12
 ls  2670177.697113434:  7f0dfdbce03c _dl_start+0xc   mov %rdi, %r12
 ls  2670177.697113434:  7f0dfdbce03f _dl_start+0xf   pushq  %rbx
 ls  2670177.697113434:  7f0dfdbce040 _dl_start+0x10  sub $0x38, %rsp
 ls  2670177.697113434:  7f0dfdbce044 _dl_start+0x14  rdtsc
 ls  2670177.697113434:  7f0dfdbce046 _dl_start+0x16  mov %eax, %eax
 ls  2670177.697113434:  7f0dfdbce048 _dl_start+0x18  shl $0x20, %rdx
 ls  2670177.697113434:  7f0dfdbce04c _dl_start+0x1c  or %rax, %rdx
 ls  2670177.697114471:  7f0dfdbce04f _dl_start+0x1f  movq  0x27e22(%rip), %rax        IPC: 0.00 (15/1685)
 ls  2670177.697116177:  7f0dfdbce056 _dl_start+0x26  movq  %rdx, 0x27683(%rip)        IPC: 0.00 (1/881)

Note, the IPC values are low due to page faults at the beginning of
execution. The additional cycles are due to the time to enter the
kernel, not the actual kernel page fault handler.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20190520113728.14389-9-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>