perf probe: Load map before glob matching

perf probe: Load map before glob matching

Commit 4c859351226c920b227fec040a3b447f0d482af3 ("perf probe: Support
glob wildcards for function name") introduces a problem:

  # /root/perf probe kmem_cache_free
 Failed to find symbol kmem_cache_free in kernel
   Error: Failed to add events.

The reason is the replacement of map__for_each_symbol_by_name() (by
map__for_each_symbol()). Although their names are similar,
map__for_each_symbol doesn't call map__load() and dso__sort_by_name()
before searching. The missing of map__load() causes this problem because
it search symbol before load dso map.

This patch ensures map__load() is called before using
map__for_each_symbol().

After this patch:

 # /root/perf probe kmem_cache_free
  Added new event:
    probe:kmem_cache_free (on kmem_cache_free%return)

You can now use it in all perf tools, such as:

        perf record -e probe:kmem_cache_free -aR sleep 1

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1431692084-46287-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>