perf tools: Missing c2c command in command-list

Add the c2c command to command-list.txt so perf help can list this
command.

Committer notes:

Before:

# perf help | grep c2c
#

After:

# perf help | grep c2c
c2c Shared Data C2C/HITM Analyzer.
#

Signed-off-by: Changbin Du <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/command-list.txt

···
 perf-buildid-list		mainporcelain common
 perf-data			mainporcelain common
 perf-diff			mainporcelain common
+perf-c2c			mainporcelain common
 perf-config			mainporcelain common
 perf-evlist			mainporcelain common
 perf-ftrace			mainporcelain common