Make use of the Index library through the index-test tool.

'index-test' is now able to provide additional info for a Decl, through multiple AST files:
-Find declarations
-Find definitions
-Find references

llvm-svn: 74803
diff --git a/clang/test/Index/t2.c b/clang/test/Index/t2.c
new file mode 100644
index 0000000..8e405cc
--- /dev/null
+++ b/clang/test/Index/t2.c
@@ -0,0 +1,8 @@
+#include "foo.h"
+
+int global_var = 10;
+
+void bar_func(void) {
+  global_var += 100;
+  foo_func(global_var);
+}