Adding memdup function to duplicate region of memory.

  void *memdup(const void *src, size_t len)
Signed-off-by: NJiri Olsa <jolsa@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1347295819-23177-3-git-send-email-jolsa@redhat.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

To cure a bunch of:

In file included from util/include/linux/bitmap.h:1,
                 from util/header.h:8,
                 from builtin-trace.c:7:
util/include/../../../../include/linux/bitmap.h:8:26: error:
linux/string.h: No such file or directory make: ***
[builtin-trace.o] Error 1 make: *** Waiting for unfinished
jobs....
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1255972296-11500-1-git-send-email-acme@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>