Installed-header hygiene (BZ#20366): time.h types.

Many headers are expected to expose a subset of the type definitions
in time.h.  time.h has a whole bunch of messy logic for conditionally
defining some its types and structs, but, as best I can tell, this
has never worked 100%.  In particular, __need_timespec is ineffective
if _TIME_H has already been defined, which means that if you compile

  #include <time.h>
  #include <sched.h>

with e.g. -fsyntax-only -std=c89 -Wall -Wsystem-headers, you will get

In file included from test.c:2:0:
/usr/include/sched.h:74:57: warning: "struct timespec" declared inside
  parameter list will not be visible outside of this definition or declaration
 extern int sched_rr_get_interval (__pid_t __pid, struct timespec *__t) __THROW;
                                                         ^~~~~~~~

And if you want to _use_ sched_rr_get_interval in a TU compiled that
way, you're hosed.

This patch replaces all of that with small bits/types/TYPE.h headers
as introduced earlier.  time.h and bits/time.h are now *much* simpler,
and a lot of other headers are slightly simpler.

	* time/time.h, bits/time.h, sysdeps/unix/sysv/linux/bits/time.h:
	Remove all logic conditional on __need macros.  Move all the
	conditionally defined types to their own headers...
	* time/bits/types/clock_t.h: Define clock_t here.
	* time/bits/types/clockid_t.h: Define clockid_t here.
	* time/bits/types/struct_itimerspec.h: Define struct itimerspec here.
	* time/bits/types/struct_timespec.h: Define struct timespec here.
	* time/bits/types/struct_timeval.h: Define struct timeval here.
	* time/bits/types/struct_tm.h: Define struct tm here.
	* time/bits/types/time_t.h: Define time_t here.
	* time/bits/types/timer_t.h: Define timer_t here.
	* time/Makefile: Install the new headers.

	* bits/resource.h, io/fcntl.h, io/sys/poll.h, io/sys/stat.h
	* io/utime.h, misc/sys/select.h, posix/sched.h, posix/sys/times.h
	* posix/sys/types.h, resolv/netdb.h, rt/aio.h, rt/mqueue.h
	* signal/signal.h, pthread/semaphore.h, sysdeps/nptl/pthread.h
	* sysdeps/unix/sysv/linux/alpha/bits/resource.h
	* sysdeps/unix/sysv/linux/alpha/sys/acct.h
	* sysdeps/unix/sysv/linux/bits/resource.h
	* sysdeps/unix/sysv/linux/bits/timex.h
	* sysdeps/unix/sysv/linux/mips/bits/resource.h
	* sysdeps/unix/sysv/linux/net/ppp_defs.h
	* sysdeps/unix/sysv/linux/sparc/bits/resource.h
	* sysdeps/unix/sysv/linux/sys/acct.h
	* sysdeps/unix/sysv/linux/sys/timerfd.h
	* sysvipc/sys/msg.h, sysvipc/sys/sem.h, sysvipc/sys/shm.h
	* time/sys/time.h, time/sys/timeb.h
	Use the new bits/types headers.

	* include/time.h: Remove __need logic.
	* include/bits/time.h
	* include/bits/types/clock_t.h, include/bits/types/clockid_t.h
	* include/bits/types/time_t.h, include/bits/types/timer_t.h
	* include/bits/types/struct_itimerspec.h
	* include/bits/types/struct_timespec.h
	* include/bits/types/struct_timeval.h
	* include/bits/types/struct_tm.h:
	New wrapper headers.

3 files changed, 10 insertions, 12 deletions

diff --git a/posix/sched.h b/posix/sched.h
index 253c963..5b431c6 100644
--- a/posix/sched.h
+++ b/posix/sched.h
@@ -25,13 +25,14 @@
 #include <bits/types.h>
 
 #define __need_size_t
+#define __need_NULL
 #include <stddef.h>
 
-#ifdef __USE_XOPEN2K
-# define __need_time_t
-# define __need_timespec
+#include <bits/types/time_t.h>
+#include <bits/types/struct_timespec.h>
+#ifndef __USE_XOPEN2K
+# include <time.h>
 #endif
-#include <time.h>
 
 #ifndef __pid_t_defined
 typedef __pid_t pid_t;
diff --git a/posix/sys/times.h b/posix/sys/times.h
index a877d14..c7308d2 100644
--- a/posix/sys/times.h
+++ b/posix/sys/times.h
@@ -24,9 +24,7 @@
 
 #include <features.h>
 
-#define	__need_clock_t
-#include <time.h>
-
+#include <bits/types/clock_t.h>
 
 __BEGIN_DECLS
 
diff --git a/posix/sys/types.h b/posix/sys/types.h
index 83dadcd..386f3e5 100644
--- a/posix/sys/types.h
+++ b/posix/sys/types.h
@@ -124,12 +124,11 @@ typedef __key_t key_t;
 #endif
 
 #if defined __USE_XOPEN || defined __USE_XOPEN2K8
-# define __need_clock_t
+# include <bits/types/clock_t.h>
 #endif
-#define	__need_time_t
-#define __need_timer_t
-#define __need_clockid_t
-#include <time.h>
+#include <bits/types/clockid_t.h>
+#include <bits/types/time_t.h>
+#include <bits/types/timer_t.h>
 
 #ifdef __USE_XOPEN
 # ifndef __useconds_t_defined