When reading the AST, delay loading of the redeclaration chain to avoid deeply nested calls.
Temporarily set the first (canonical) declaration as the previous one, which is the one that
matters, and mark the real previous DeclID to be loaded & attached later on.

Fixes rdar://8956193.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@125434 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Index/c-index-redecls.c b/test/Index/c-index-redecls.c
new file mode 100644
index 0000000..0cf2f03
--- /dev/null
+++ b/test/Index/c-index-redecls.c
@@ -0,0 +1,107 @@
+// RUN: %clang_cc1 -emit-pch -o %t.ast %s
+// RUN: c-index-test -test-load-tu %t.ast all
+
+// rdar://8956193 - We would blow the thread stack because of nested calls due
+//                  to redeclarations.
+
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);
+void socrates(void);