emacs_read and emacs_write now use void *, not char *.

emacs_read and emacs_write now use void *, not char *.

* alloc.c (valid_pointer_p) [!WINDOWSNT]: Remove now-unnecessary cast.
* sysdep.c (emacs_read, emacs_write, emacs_write_sig):
Buffer arg is now void *, not char *.  This matches plain
'read' and 'write' better, and avoids a constraint violation
on Solaris 9 with Oracle Studio.