perf record: Mark MAP_HUGETLB when synthesizing mmap events

perf record: Mark MAP_HUGETLB when synthesizing mmap events

When synthesizing mmap events, add MAP_HUGETLB map flag if the source of
mapping is file in hugetlbfs.

After this patch, perf can identify hugetlb mapping even if perf is
started after the mapping of huge pages (like with 'perf top').

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Reviewed-by: Nilay Vaish <nilayvaish@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Hou Pengyang <houpengyang@huawei.com>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1473137909-142064-4-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>