Remove __ASSUME_SIGNALFD4.

Current Linux kernel version requirements mean the signalfd4 syscall
can always be assumed to be available.  This patch removes
__ASSUME_SIGNALFD4 and associated conditionals.

Tested for x86_64 and x86 that installed stripped shared libraries are
unchanged by the patch.

	* sysdeps/unix/sysv/linux/kernel-features.h (__ASSUME_SIGNALFD4):
	Remove macro.
	* sysdeps/unix/sysv/linux/signalfd.c: Do not include
	<kernel-features.h>.
	(signalfd) [__NR_signalfd4]: Make code unconditional.
	(signalfd) [!__ASSUME_SIGNALFD4]: Remove conditional code.

ChangeLog

@@ -1,3 +1,12 @@
+2016-03-21  Joseph Myers  <joseph@codesourcery.com>
+
+	* sysdeps/unix/sysv/linux/kernel-features.h (__ASSUME_SIGNALFD4):
+	Remove macro.
+	* sysdeps/unix/sysv/linux/signalfd.c: Do not include
+	<kernel-features.h>.
+	(signalfd) [__NR_signalfd4]: Make code unconditional.
+	(signalfd) [!__ASSUME_SIGNALFD4]: Remove conditional code.
+
 2016-03-21  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	* sysdeps/unix/sysv/linux/spawni.c (__spawnix): Fix implict checks

sysdeps/unix/sysv/linux/kernel-features.h

@@ -83,7 +83,6 @@
    2.6.27.  */
 #define __ASSUME_IN_NONBLOCK	1
 #define __ASSUME_PIPE2		1
-#define __ASSUME_SIGNALFD4	1
 #define __ASSUME_DUP3		1
 
 /* Support for accept4 functionality was added in 2.6.28, but for some

sysdeps/unix/sysv/linux/signalfd.c

@@ -19,34 +19,10 @@
 #include <signal.h>
 #include <sys/signalfd.h>
 #include <sysdep.h>
-#include <kernel-features.h>
 
 
 int
 signalfd (int fd, const sigset_t *mask, int flags)
 {
-#ifdef __NR_signalfd4
-  int res = INLINE_SYSCALL (signalfd4, 4, fd, mask, _NSIG / 8, flags);
-# ifndef __ASSUME_SIGNALFD4
-  if (res != -1 || errno != ENOSYS)
-# endif
-    return res;
-#endif
-
-#ifndef __ASSUME_SIGNALFD4
-  /* The old system call has no flag parameter which is bad.  So we have
-     to wait until we have to support to pass additional values to the
-     kernel (sys_indirect) before implementing setting flags like
-     O_NONBLOCK etc.  */
-  if (flags != 0)
-    return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
-
-# ifdef __NR_signalfd
-  return INLINE_SYSCALL (signalfd, 3, fd, mask, _NSIG / 8);
-# else
-  return INLINE_SYSCALL_ERROR_RETURN_VALUE (ENOSYS);
-# endif
-#elif !defined __NR_signalfd4
-# error "__ASSUME_SIGNALFD4 defined but not __NR_signalfd4"
-#endif
+  return INLINE_SYSCALL (signalfd4, 4, fd, mask, _NSIG / 8, flags);
 }