perf tools: replace mkostemp with mkstemp

perf tools: replace mkostemp with mkstemp

The mkostemp function is only available in glibc. This leads to compile
error in Android, since bionic is derived from BSD.

Replacing mkostemp with mkstemp. mkstemp is available on both glibc and
bionic.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1347065004-15306-10-git-send-email-irina.tirdea@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>