* posix.c: don't include <sys/select.h> or define macros for

	* posix.c: don't include <sys/select.h> or define macros for
	select, since they were not used in this file.

*	* filesys.c (scm_select): make the fifth parameter microseconds,
	not milliseconds.  let the fourth parameter be either a real value
	or an integer or #f.  The first, second and third arguments can
	now be vectors: the type of the corresponding return set will be
	the same.
	(set_element, get_element): new static procedures.