perf scripts python: exported-sql-viewer.py: Fix Array TypeError

The 'Array' class is present in more than one python standard library.
In some versions of Python 3, the following error occurs:

Traceback (most recent call last):
  File "tools/perf/scripts/python/exported-sql-viewer.py", line 4702, in <lambda>
    reports_menu.addAction(CreateAction(label, "Create a new window displaying branch events", lambda a=None,x=dbid: self.NewBranchView(x), self))
  File "tools/perf/scripts/python/exported-sql-viewer.py", line 4727, in NewBranchView
    BranchWindow(self.glb, event_id, ReportVars(), self)
  File "tools/perf/scripts/python/exported-sql-viewer.py", line 3208, in __init__
    self.model = LookupCreateModel(model_name, lambda: BranchModel(glb, event_id, report_vars.where_clause))
  File "tools/perf/scripts/python/exported-sql-viewer.py", line 343, in LookupCreateModel
    model = create_fn()
  File "tools/perf/scripts/python/exported-sql-viewer.py", line 3208, in <lambda>
    self.model = LookupCreateModel(model_name, lambda: BranchModel(glb, event_id, report_vars.where_clause))
  File "tools/perf/scripts/python/exported-sql-viewer.py", line 3124, in __init__
    self.fetcher = SQLFetcher(glb, sql, prep, self.AddSample)
  File "tools/perf/scripts/python/exported-sql-viewer.py", line 2658, in __init__
    self.buffer = Array(c_char, self.buffer_size, lock=False)
TypeError: abstract class

This apparently happens because Python can be inconsistent about which
class of the name 'Array' gets imported. Fix by importing explicitly by
name so that only the desired 'Array' gets imported.

Fixes: 8392b74b

 ("perf scripts python: exported-sql-viewer.py: Add ability to display all the database tables")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/20210521092053.25683-3-adrian.hunter@intel.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>