* async.h (scm_call_with_blocked_asyncs,

* async.h (scm_call_with_blocked_asyncs,
scm_call_with_unblocked_asyncs, scm_c_call_with_blocked_asyncs,
scm_c_call_with_unblocked_asyncs): New prototypes.
(scm_mask_signals, scm_unmask_signals): Deprecated.
(scm_mask_ints): Turned into a macro.

* async.c (scm_mask_ints): Removed.
(scm_run_asyncs): Do not set scm_mask_ints while running an async.
this should not be necessary.
(scm_async_click): Test block_asyncs instead of scm_mask_ints.
(scm_mask_signals, scm_unmask_signals): Deprecated.  Emit
deprecation warning and check for errornous use.  Set block_asyncs
instead of scm_mask_ints.
(increase_block, decrease_block, scm_call_with_blocked_asyncs,
scm_call_with_unblocked_asyncs, scm_c_call_with_blocked_asyncs,
scm_c_call_with_unblocked_asyncs): New.