Eliminate Clang warning for GC_pthread_exit attribute

* include/gc_pthread_redirects.h (GC_PTHREAD_EXIT_DECLARED): Test and
define new macro (only if GC_PTHREAD_EXIT_ATTRIBUTE) to prevent Clang
warning "attribute declaration must precede definition" for
GC_pthread_exit when this header included from extra/gc.c tail.

diff --git a/include/gc_pthread_redirects.h b/include/gc_pthread_redirects.h
index b4b2b13..37cb249 100644 (file)
--- a/include/gc_pthread_redirects.h
+++ b/include/gc_pthread_redirects.h
@@ -58,7 +58,8 @@ GC_API int GC_pthread_detach(pthread_t);
   GC_API int GC_pthread_cancel(pthread_t);
 #endif
 
-#ifdef GC_PTHREAD_EXIT_ATTRIBUTE
+#if defined(GC_PTHREAD_EXIT_ATTRIBUTE) && !defined(GC_PTHREAD_EXIT_DECLARED)
+# define GC_PTHREAD_EXIT_DECLARED
   GC_API void GC_pthread_exit(void *) GC_PTHREAD_EXIT_ATTRIBUTE;
 #endif