perf stat: Do not fail on metrics on s390 z/VM systems

On s390 z/VM virtual machines command 'perf list' also displays metrics:

# perf list | grep -A 20 'Metric Groups:'
Metric Groups:

No_gr

perf stat: Do not fail on metrics on s390 z/VM systems

On s390 z/VM virtual machines command 'perf list' also displays metrics:

# perf list | grep -A 20 'Metric Groups:'
Metric Groups:

No_group:
cpi
[Cycles per Instruction]
est_cpi
[Estimated Instruction Complexity CPI infinite Level 1]
finite_cpi
[Cycles per Instructions from Finite cache/memory]
l1mp
[Level One Miss per 100 Instructions]
l2p
[Percentage sourced from Level 2 cache]
l3p
[Percentage sourced from Level 3 on same chip cache]
l4lp
[Percentage sourced from Level 4 Local cache on same book]
l4rp
[Percentage sourced from Level 4 Remote cache on different book]
memp
[Percentage sourced from memory]
....
#

The command

# perf stat -M cpi -- true
event syntax error: '{CPU_CYCLES/metric-id=CPU_CYCLES/.....'
\___ Bad event or PMU

Unable to find PMU or event on a PMU of 'CPU_CYCLES'

event syntax error: '{CPU_CYCLES/metric-id=CPU_CYCLES/...'
\___ Cannot find PMU `CPU_CYCLES'.
Missing kernel support?
#

fails. 'perf stat' should not fail on metrics when the referenced CPU
Counter Measurement PMU is not available.

Output after:

# perf stat -M est_cpi -- sleep 1

Performance counter stats for 'sleep 1':

1,000,887,494 ns duration_time # 0.00 est_cpi

1.000887494 seconds time elapsed

0.000143000 seconds user
0.000662000 seconds sys

#

Fixes: 7f76b31130680fb3 ("perf list: Add IBM z16 event description for s390")
Suggested-by: Ian Rogers <irogers@google.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20240404064806.1362876-2-tmricht@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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