perf top: Fix window dimensions change handling

The stdio perf top crashes when we change the terminal
window size. The reason is that we assumed we get the
perf_top pointer as a signal handler argument which is
not the case.

Changing the SIGWINCH handler logic to change global
resize variable, which is checked in the main thread
loop.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ysuzwz77oev1ftgvdscn9bpu@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>