perf docs: Fix accidental em-dashes

" -- " is an em dash (—) in asciidoc, so all these examples that were
supposed to be producing a literal two dashes were being misrendered.

Signed-off-by: Alyssa Ross <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lore.kernel.org/lkml/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/intel-hybrid.txt

···
 One example, 'triad_loop' runs on cpu16 (atom core), while we can see the
 scaled value for core cycles is 160,444,092 and the percentage is 0.47%.
 
-perf stat -e cycles -- taskset -c 16 ./triad_loop
+perf stat -e cycles \-- taskset -c 16 ./triad_loop
 
 As previous, two events are created.
 

tools/perf/Documentation/perf-c2c.txt

···
 --------
 [verse]
 'perf c2c record' [<options>] <command>
-'perf c2c record' [<options>] -- [<record command options>] <command>
+'perf c2c record' [<options>] \-- [<record command options>] <command>
 'perf c2c report' [<options>]
 
 DESCRIPTION

tools/perf/Documentation/perf-iostat.txt

···
 --------
 [verse]
 'perf iostat' list
-'perf iostat' <ports> -- <command> [<options>]
+'perf iostat' <ports> \-- <command> [<options>]
 
 DESCRIPTION
 -----------

tools/perf/Documentation/perf-record.txt

···
 --------
 [verse]
 'perf record' [-e <EVENT> | --event=EVENT] [-a] <command>
-'perf record' [-e <EVENT> | --event=EVENT] [-a] -- <command> [<options>]
+'perf record' [-e <EVENT> | --event=EVENT] [-a] \-- <command> [<options>]
 
 DESCRIPTION
 -----------

tools/perf/Documentation/perf-stat.txt

···
 --------
 [verse]
 'perf stat' [-e <EVENT> | --event=EVENT] [-a] <command>
-'perf stat' [-e <EVENT> | --event=EVENT] [-a] -- <command> [<options>]
-'perf stat' [-e <EVENT> | --event=EVENT] [-a] record [-o file] -- <command> [<options>]
+'perf stat' [-e <EVENT> | --event=EVENT] [-a] \-- <command> [<options>]
+'perf stat' [-e <EVENT> | --event=EVENT] [-a] record [-o file] \-- <command> [<options>]
 'perf stat' report [-i file]
 
 DESCRIPTION
···
 
 Log output to fd, instead of stderr.  Complementary to --output, and mutually exclusive
 with it.  --append may be used here.  Examples:
-     3>results  perf stat --log-fd 3          -- $cmd
-     3>>results perf stat --log-fd 3 --append -- $cmd
+     3>results  perf stat --log-fd 3          \-- $cmd
+     3>>results perf stat --log-fd 3 --append \-- $cmd
 
 --control=fifo:ctl-fifo[,ack-fifo]::
 --control=fd:ctl-fd[,ack-fd]::
···
 
  perf stat -D -1 -e cpu-cycles -a -I 1000       \
            --control fd:${ctl_fd},${ctl_fd_ack} \
-           -- sleep 30 &
+           \-- sleep 30 &
  perf_pid=$!
 
  sleep 5  && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})"
···
 --post::
 	Pre and post measurement hooks, e.g.:
 
-perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' -- make -s -j64 O=defconfig-build/ bzImage
+perf stat --repeat 10 --null --sync --pre 'make -s O=defconfig-build/clean' \-- make -s -j64 O=defconfig-build/ bzImage
 
 -I msecs::
 --interval-print msecs::
···
 EXAMPLES
 --------
 
-$ perf stat -- make
+$ perf stat \-- make
 
    Performance counter stats for 'make':