libc: Fix C23 version macro visibility

In headers that existed prior to C23, these should be visible only in
C23 or BSD mode.

Fixes:		0fe73dcf7c ("libc: Add <assert.h> C23 feature test macro")
Fixes:		1f09e35429 ("sys/limits.h: Add BOOL_MAX, BITINT_MAXWIDTH, and C23 feature test macro")
Fixes:		cd0727ec70 ("libc: Add <stdio.h> C23 feature test macro")
Fixes:		fc9d02cb29 ("libc: Add <time.h> C23 feature test macro")
Fixes:		4aeed6e9d2 ("libc: Add <setjmp.h> C23 feature test macro")
Reviewed by:	fuz, kfv, dteske
Differential Revision:	https://reviews.freebsd.org/D59272

include/assert.h

@@ -71,7 +71,9 @@
 #ifndef _ASSERT_H_
 #define _ASSERT_H_
 
+#if __ISO_C_VISIBLE >= 2023 || __BSD_VISIBLE
 #define __STDC_VERSION_ASSERT_H__	202311L
+#endif
 
 /*
  * Static assertions.  In principle we could define static_assert for

include/limits.h

@@ -32,10 +32,12 @@
 #ifndef _LIMITS_H_
 #define _LIMITS_H_
 
-#define __STDC_VERSION_LIMITS_H__	202311L
-
 #include <sys/cdefs.h>
 
+#if __ISO_C_VISIBLE >= 2023 || __BSD_VISIBLE
+#define __STDC_VERSION_LIMITS_H__	202311L
+#endif
+
 #if __POSIX_VISIBLE
 #define	_POSIX_ARG_MAX		4096
 #define	_POSIX_LINK_MAX		8

include/setjmp.h

@@ -37,10 +37,12 @@
 #ifndef _SETJMP_H_
 #define _SETJMP_H_
 
-#define __STDC_VERSION_SETJMP_H__	202311L
-
 #include <sys/cdefs.h>
 
+#if __ISO_C_VISIBLE >= 2023 || __BSD_VISIBLE
+#define __STDC_VERSION_SETJMP_H__	202311L
+#endif
+
 /* The size of the jmp_buf is machine dependent: */
 #include <machine/setjmp.h>
 

include/stdio.h

@@ -35,12 +35,14 @@
 #ifndef	_STDIO_H_
 #define	_STDIO_H_
 
-#define __STDC_VERSION_STDIO_H__	202311L
-
 #include <sys/cdefs.h>
 #include <sys/_null.h>
 #include <sys/_types.h>
 
+#if __ISO_C_VISIBLE >= 2023 || __BSD_VISIBLE
+#define __STDC_VERSION_STDIO_H__	202311L
+#endif
+
 __NULLABILITY_PRAGMA_PUSH
 
 typedef	__off_t		fpos_t;

include/time.h

@@ -37,13 +37,15 @@
 #ifndef _TIME_H_
 #define	_TIME_H_
 
-#define __STDC_VERSION_TIME_H__	202311L
-
 #include <sys/cdefs.h>
 #include <sys/_null.h>
 #include <sys/_types.h>
 #include <sys/_clock_id.h>
 
+#if __ISO_C_VISIBLE >= 2023 || __BSD_VISIBLE
+#define __STDC_VERSION_TIME_H__	202311L
+#endif
+
 #if __POSIX_VISIBLE > 0 && __POSIX_VISIBLE < 200112 || __BSD_VISIBLE
 /*
  * Frequency of the clock ticks reported by times().  Deprecated - use