Installed-header hygiene (BZ#20366): stack_t.

sys/ucontext.h unconditionally uses stack_t, and it does not make
sense to change that.  But signal.h only declares stack_t under
__USE_XOPEN_EXTENDED || __USE_XOPEN2K8.  The actual definition is
already in a bits header, bits/sigstack.h, but that header insists on
only being included by signal.h, so we have to change that as well as
all of the sys/ucontext.h variants.  (Some but not all variants of
bits/sigcontext.h, which sys/ucontext.h may also need, had already
received this adjustment; for consistency, I made them all the same,
even if that's not strictly necessary in some configurations.)
bits/sigcontext.h and bits/sigstack.h also all need to receive
multiple inclusion guards.

	* sysdeps/generic/sys/ucontext.h
	* sysdeps/arm/sys/ucontext.h
	* sysdeps/i386/sys/ucontext.h
	* sysdeps/m68k/sys/ucontext.h
	* sysdeps/mips/sys/ucontext.h
	* sysdeps/unix/sysv/linux/aarch64/sys/ucontext.h
	* sysdeps/unix/sysv/linux/alpha/sys/ucontext.h
	* sysdeps/unix/sysv/linux/arm/sys/ucontext.h
	* sysdeps/unix/sysv/linux/hppa/sys/ucontext.h
	* sysdeps/unix/sysv/linux/ia64/sys/ucontext.h
	* sysdeps/unix/sysv/linux/m68k/sys/ucontext.h
	* sysdeps/unix/sysv/linux/mips/sys/ucontext.h
	* sysdeps/unix/sysv/linux/nios2/sys/ucontext.h
	* sysdeps/unix/sysv/linux/powerpc/sys/ucontext.h
	* sysdeps/unix/sysv/linux/s390/sys/ucontext.h
	* sysdeps/unix/sysv/linux/sh/sys/ucontext.h
	* sysdeps/unix/sysv/linux/sparc/sys/ucontext.h
	* sysdeps/unix/sysv/linux/tile/sys/ucontext.h
	* sysdeps/unix/sysv/linux/x86/sys/ucontext.h:
	Include both bits/sigcontext.h and bits/sigstack.h.
	Fix grammar error in comment, if present.

	* bits/sigstack.h
	* sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h
	* sysdeps/unix/sysv/linux/alpha/bits/sigstack.h
	* sysdeps/unix/sysv/linux/bits/sigstack.h
	* sysdeps/unix/sysv/linux/ia64/bits/sigstack.h
	* sysdeps/unix/sysv/linux/mips/bits/sigstack.h
	* sysdeps/unix/sysv/linux/powerpc/bits/sigstack.h
	* sysdeps/unix/sysv/linux/sparc/bits/sigstack.h
	* bits/sigcontext.h
	* sysdeps/mach/hurd/i386/bits/sigcontext.h
	* sysdeps/unix/sysv/linux/bits/sigcontext.h
	* sysdeps/unix/sysv/linux/ia64/bits/sigcontext.h
	* sysdeps/unix/sysv/linux/sparc/bits/sigcontext.h:
	Add multiple inclusion guard.  Permit inclusion by sys/ucontext.h
	as well as signal.h, if this was not already allowed.  Request
	definition of size_t if necessary.  Minimize semantically-null
	differences across files.

2 files changed, 12 insertions, 2 deletions

diff --git a/bits/sigcontext.h b/bits/sigcontext.h
index 85b2a96d9f..ddc4966d6b 100644
--- a/bits/sigcontext.h
+++ b/bits/sigcontext.h
@@ -16,7 +16,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGCONTEXT_H
+#define _BITS_SIGCONTEXT_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never use <bits/sigcontext.h> directly; include <signal.h> instead."
 #endif
 
@@ -30,3 +33,5 @@ struct sigcontext
   };
 
 /* Signal subcodes should be defined here.  */
+
+#endif /* bits/sigcontext.h */
diff --git a/bits/sigstack.h b/bits/sigstack.h
index b4b911e7d1..62020b396e 100644
--- a/bits/sigstack.h
+++ b/bits/sigstack.h
@@ -16,7 +16,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#ifndef _SIGNAL_H
+#ifndef _BITS_SIGSTACK_H
+#define _BITS_SIGSTACK_H 1
+
+#if !defined _SIGNAL_H && !defined _SYS_UCONTEXT_H
 # error "Never include this file directly.  Use <signal.h> instead"
 #endif
 
@@ -52,3 +55,5 @@ enum
 
 /* System default stack size.  */
 #define SIGSTKSZ	(MINSIGSTKSZ + 32768)
+
+#endif /* bits/sigstack.h */