bug#15807: guile-2.0.9 doesn't handle Apple clang < 5 or llvm.org clang < 3.3 properly

[Jack Howarth]

    The guile 2.0.9 sources incorrectly assumes that sll clang compilers support
the noreturn attribute which was only added in llvm.org clang 3.3 and Apple 
clang 5.0.
In fink, we have fixed this with the following patch...

--- guile-2.0.9/libguile/__scm.h.orig   2013-11-01 22:57:06.000000000 -0400
+++ guile-2.0.9/libguile/__scm.h        2013-11-01 23:07:03.000000000 -0400
@@ -76,7 +76,10 @@
  * Examples:
  *   1) int foo (char arg) SCM_NORETURN;
  */
-#ifdef __GNUC__
+
+#if (defined(__apple_build_version__) && (__clang_major__ < 5)) || 
((__clang_major__ < 3) && (__clang_minor__ < 3))
+#define SCM_NORETURN
+#elif defined(__GNUC__) 
 #define SCM_NORETURN __attribute__ ((noreturn))
 #else
 #define SCM_NORETURN

Since the environmentals for __clang__, __clang_major__ and __clang_minor are 
common to both Apple and llvm.org
clang, the (defined(__apple_build_version__) is used to limit the first test on 
(__clang_major__ < 5) to Apple
clang. the second test for ((__clang_major__ < 3) && (__clang_minor__ < 3)) 
requires no additional restriction
since it is valid for both Apple and llvm clang in that version range. Without 
this patch, builds on Xcode 4.6.3,
which uses Apple clang 4.2 that lacks noreturn attribute support will fail.
          Jack