g_signal_handlers_block_matched() prototype

[John Lindgren <john lindgren aol com>]

Hi,

The <func> argument passed to g_signal_handlers_block_matched() is
currently a gpointer, which causes a warning when GCC is in strict C99
mode, since C99 does not allow converting a function pointer to an
object pointer.  Wouldn't it make more sense for <func> to have
GCallback type?

-- John Lindgren