tests/test-gendoc-zh_CN.t

bookmarks: directly use base dict 'setitem'

The bmstore '__setitem__' method is setting an extra flag that is not needed
during initialization. Skipping the method will allow further cleanup and yield
some speedup as a side effect.

Before:
! wall 0.009120 comb 0.010000 user 0.010000 sys 0.000000 (best of 312)

After:
! wall 0.007874 comb 0.010000 user 0.010000 sys 0.000000 (best of 360)

#require docutils gettext

  $ $TESTDIR/check-gendoc zh_CN
  checking for parse errors