perf script: Support using -f to override perf.data file ownership

perf script: Support using -f to override perf.data file ownership

Enable perf script to use perf.data when it is not owned by current user
or root. Change the short option name of --fields to -F to avoid confusion
with --force.

Example:

 # perf record ls
 # chown Yunlong.Song:Yunlong.Song perf.data
 # ls -al perf.data
 -rw------- 1 Yunlong.Song Yunlong.Song 28360 Apr  2 14:53 perf.data
 # id
 uid=0(root) gid=0(root) groups=0(root),64(pkcs11)

Before this patch:

 # perf script
 File perf.data not owned by current user or root (use -f to override)
 # perf script -f
   Error: switch `f' requires a value

  usage: perf script [<options>]
     or: perf script [<options>] record <script> [<record-options>] <command>
     or: perf script [<options>] report <script> [script-args]
     or: perf script [<options>] <script> [<record-options>] <command>
     or: perf script [<options>] <top-script> [script-args]

     -f, --fields <str>    comma separated output fields prepend with
     'type:'. Valid types: hw,sw,trace,raw. Fields:
     comm,tid,pid,time,cpu,event,trace,ip,sym,dso,addr,symoff,period

As shown above, the -f option does not work at all. And -f is already
taken up by --fields, which makes --force confused, so change the short
option name of --fields to -F like what other perf commands do (e.g.
perf report -F) and use -f as the short option name of --force.

After this patch:

 # perf script
 File perf.data not owned by current user or root (use -f to override)
 # perf script -f
 :41298 41298 2590086.564226:          1 cycles:  ffffffff8103efc6
 native_write_msr_safe ([kernel.kallsyms])
 :41298 41298 2590086.564244:          1 cycles:  ffffffff8103efc6
 native_write_msr_safe ([kernel.kallsyms])
 :41298 41298 2590086.564249:          7 cycles:  ffffffff8103efc6
 native_write_msr_safe ([kernel.kallsyms])
 :41298 41298 2590086.564255:        176 cycles:  ffffffff8103efc6
 native_write_msr_safe ([kernel.kallsyms])
     ls 41298 2590086.567346:       4059 cycles:  ffffffff8105a592
     raise_softirq ([kernel.kallsyms])
     ls 41298 2590086.567353:       3717 cycles:  ffffffff8105a592
     raise_softirq ([kernel.kallsyms])
     ls 41298 2590086.567358:      63058 cycles:  ffffffff8105a592
     raise_softirq ([kernel.kallsyms])
     ls 41298 2590086.567448:    1706255 cycles:            406ae0
     [unknown] (/usr/bin/ls)

As shown above, the -f option really works now.

Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1427982439-27388-8-git-send-email-yunlong.song@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>