updated for version 7.3.974

Problem:    Can't build with ruby 1.8.5.
Solution:   Only use ruby_init_stack() when RUBY_INIT_STACK is defined.
            (Yukihiro Nakadaira)

src/version.c

@@ -728,6 +728,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    974,
 /**/
     973,
 /**/