feature tests: do not re-include <stdio.h>

iffe --man documents that stdio.h is automatically pre-included for
all feature tests. Including it in the test code is not needed.

You'd think it shouldn't do any harm, but on a Gentoo i386 system,
this include turned out to be the cause of a mysterious 'unknown
type: off64_t' error while compiling the output{ ... }end block in
features/pty. I'm not going to bother with further tracing the
cause of that -- there is some hackery with off64_t defines in the
AST headers that probably has something to do with it.

src/cmd/builtin/features/pty,
src/lib/libast/features/float,
src/lib/libast/features/sfio,
src/lib/libast/features/stdio:
- Remove '#include <stdio.h>' from output{ ... }end blocks.

src/cmd/builtin/features/pty

@@ -13,7 +13,6 @@ lib	openpty,_getpty,ptsname -lutil
 lib	grantpt,unlockpt,posix_openpt stdlib.h
 
 tst - output{
-	#include	<stdio.h>
 	#include	<sys/types.h>
 	#include	<sys/stat.h>
 	#if _lib_ptsname && _npt_ptsname

src/lib/libast/features/float

@@ -245,7 +245,6 @@ macro{
 
 tst	- note{ missing floating point limits }end output{
 	#include "FEATURE/common"
-	#include <stdio.h>
 	#if _hdr_float
 	#include <float.h>
 	#endif
@@ -900,7 +899,6 @@ tst	- note{ missing floating point limits }end output{
 
 tst	- note{ double exponent bitfoolery }end output{
 	#include "FEATURE/common"
-	#include <stdio.h>
 	typedef union _dbl_exp_u
 	{
 		unsigned _ast_int4_t	e[sizeof(double) / 4];
@@ -936,7 +934,6 @@ tst	- note{ double exponent bitfoolery }end output{
 
 tst	- note{ long double exponent bitfoolery }end output{
 	#include "FEATURE/common"
-	#include <stdio.h>
 	typedef union _ast_fltmax_exp_u
 	{
 		unsigned _ast_int4_t	e[sizeof(_ast_fltmax_t) / 4];
@@ -971,7 +968,6 @@ tst	- note{ long double exponent bitfoolery }end output{
 }end
 
 tst	- -DN=1 - -DN=2 note{ _ast_fltmax_t maximum integral type }end output{
-	#include <stdio.h>
 	int
 	main()
 	{
@@ -996,7 +992,6 @@ tst	- -DSCAN=1 - -lm -DSTRTO=1 - -DMAC=1 - -DDIV=1 - -DEXP=1 - -DADD=1 - -DMPY=1
 	#define _FP_MODE_VARIABLE	1
 	#endif
 	#include "FEATURE/common"
-	#include <stdio.h>
 	#include <sys/types.h>
 	#include <signal.h>
 	#include <string.h>

src/lib/libast/features/sfio

@@ -7,7 +7,6 @@ key	signed
 typ	struct.sf_hdtr sys/socket.h
 
 tst	- note{ number of bits in pointer }end output{
-	#include <stdio.h>
 	int
 	main()
 	{

src/lib/libast/features/stdio

@@ -204,7 +204,6 @@ cat{
 	#endif
 }end
 output{
-	#include <stdio.h>
 	#ifndef FILENAME_MAX
 	#ifndef NAME_MAX
 	#ifndef _POSIX_NAME_MAX