Fix siginterrupt namespace (bug 21597).

The siginterrupt function is XSI-shaded in POSIX.  glibc wrongly
declares it in <signal.h> for non-XSI POSIX.1:2008.  This patch fixes
the conditionals (moving it into the __USE_XOPEN_EXTENDED ||
__USE_MISC block as the minimum conservative change, although it's not
clear this obsolescent function should be declared by default).

Tested for x86_64.

	[BZ #21597]
	* signal/signal.h (siginterrupt): Make declaration conditional on
	[__USE_XOPEN_EXTENDED || __USE_MISC].

ChangeLog

@@ -1,5 +1,9 @@
 2017-06-19  Joseph Myers  <joseph@codesourcery.com>
 
+	[BZ #21597]
+	* signal/signal.h (siginterrupt): Make declaration conditional on
+	[__USE_XOPEN_EXTENDED || __USE_MISC].
+
 	[BZ #21584]
 	* signal/signal.h: Make includes of <bits/sigstack.h> and
 	<bits/ss_flags.h> conditional on [__USE_XOPEN_EXTENDED ||

signal/signal.h

@@ -296,11 +296,6 @@ extern int sigreturn (struct sigcontext *__scp) __THROW;
 # define __need_size_t
 # include <stddef.h>
 
-/* If INTERRUPT is nonzero, make signal SIG interrupt system calls
-   (causing them to fail with EINTR); if INTERRUPT is zero, make system
-   calls be restarted after signal SIG.  */
-extern int siginterrupt (int __sig, int __interrupt) __THROW;
-
 # include <bits/types/stack_t.h>
 # if defined __USE_XOPEN || defined __USE_XOPEN2K8
 /* This will define `ucontext_t' and `mcontext_t'.  */
@@ -309,6 +304,11 @@ extern int siginterrupt (int __sig, int __interrupt) __THROW;
 #endif /* Use POSIX.1-2008 or X/Open Unix.  */
 
 #if defined __USE_XOPEN_EXTENDED || defined __USE_MISC
+/* If INTERRUPT is nonzero, make signal SIG interrupt system calls
+   (causing them to fail with EINTR); if INTERRUPT is zero, make system
+   calls be restarted after signal SIG.  */
+extern int siginterrupt (int __sig, int __interrupt) __THROW;
+
 # include <bits/sigstack.h>
 # include <bits/ss_flags.h>