Don't use the identifier 'noreturn'.

Fixes <http://bugs.gnu.org/15798>.
Reported by Matt Sicker <boards@gmail.com>.

* libguile/__scm.h (SCM_NORETURN): Use ((__noreturn__)) instead of
  ((noreturn)).

* libguile/throw.h (scm_ithrow): Rename formal parameter from 'noreturn'
  to 'no_return'.

* libguile/throw.c (scm_ithrow): Rename formal parameter from 'noreturn'
  to 'no_return'.
---

diff --git a/libguile/__scm.h b/libguile/__scm.h
index e75f1a9..486825e 100644
--- a/libguile/__scm.h
+++ b/libguile/__scm.h
@@ -66,7 +66,7 @@
  *   1) int foo (char arg) SCM_NORETURN;
  */
 #ifdef __GNUC__
-#define SCM_NORETURN __attribute__ ((noreturn))
+#define SCM_NORETURN __attribute__ ((__noreturn__))
 #else
 #define SCM_NORETURN
 #endif
diff --git a/libguile/throw.c b/libguile/throw.c
index fcfde47..21ec196 100644
--- a/libguile/throw.c
+++ b/libguile/throw.c
@@ -684,7 +684,7 @@ SCM_DEFINE (scm_throw, "throw", 1, 0, 1,
 #undef FUNC_NAME
 
 SCM
-scm_ithrow (SCM key, SCM args, int noreturn SCM_UNUSED)
+scm_ithrow (SCM key, SCM args, int no_return SCM_UNUSED)
 {
   SCM jmpbuf = SCM_UNDEFINED;
   SCM wind_goal;
diff --git a/libguile/throw.h b/libguile/throw.h
index 84b0aa9..76f5c85 100644
--- a/libguile/throw.h
+++ b/libguile/throw.h
@@ -91,7 +91,7 @@ SCM_API SCM scm_catch_with_pre_unwind_handler (SCM tag, SCM thunk, SCM handler,
 SCM_API SCM scm_catch (SCM tag, SCM thunk, SCM handler);
 SCM_API SCM scm_with_throw_handler (SCM tag, SCM thunk, SCM handler);
 SCM_API SCM scm_lazy_catch (SCM tag, SCM thunk, SCM handler);
-SCM_API SCM scm_ithrow (SCM key, SCM args, int noreturn);
+SCM_API SCM scm_ithrow (SCM key, SCM args, int no_return);
 
 SCM_API SCM scm_throw (SCM key, SCM args);
 SCM_API void scm_init_throw (void);