perf test: Remove x permission from lib/stat_output.sh

The commit fc51fc8 factored out the helper functions to a library
but the new file had execute permission.  Due to the way it detects
the shell test scripts, it showed up in the perf test list unexpectedly.

  $ ./perf test list 2>&1 | grep 86
   76: x86 bp modify
   77: x86 Sample parsing
   78: x86 hybrid
   86:                        <---- (here)

  $ ./perf test -v 86
   86:                                                                 :
  --- start ---
  test child forked, pid 1932207
  test child finished with 0
  ---- end ----
  : Ok

As it's a collection of library functions, it should not run as is.
Let's remove the execute permission.

Fixes: fc51fc8 ("perf test: Move all the check functions of stat CSV output to lib")
Acked-by: Ian Rogers <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Ingo Molnar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>

Author: namhyung