perf list: Add debug support for outputing alias string

For debugging and testing it is useful to see the converted alias
string. Add support to perf stat/record and perf list to print the alias
conversion. The text string is saved in the alias structure.  For perf
stat/record it is folded into the normal -v. For perf list -v was taken,
so we use --debug.

Before:

% perf list
...
cache:
  l1d.replacement
       [L1D data line replacements]
  l1d_pend_miss.fb_full
       [Cycles a demand request was blocked due to Fill Buffers inavailability]

After

% perf list --debug
...
cache:
  l1d.replacement
       [L1D data line replacements]
        cpu/umask=0x1,period=2000003,event=0x51/
  l1d_pend_miss.fb_full
       [Cycles a demand request was blocked due to Fill Buffers inavailability]
        cpu/umask=0x2,period=2000003,cmask=1,event=0x48/

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20170128020345.19007-6-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>