perf tools: Add anonymous huge page recognition

perf tools: Add anonymous huge page recognition

Judging anonymous memory's vm_area_struct, perf_mmap_event's filename
will be set to "//anon" indicating this vma belongs to anonymous
memory.

Once hugepage is used, vma's vm_file points to hugetlbfs. In this way,
this vma will not be regarded as anonymous memory by is_anon_memory() in
perf user space utility.

Signed-off-by: Joshua Zhu <zhu.wen-jie@hp.com>
Cc: Akihiro Nagai <akihiro.nagai.hw@hitachi.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joshua Zhu <zhu.wen-jie@hp.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1357363797-3550-1-git-send-email-zhu.wen-jie@hp.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>