[index] Add 'Parameter' symbol kind and 'Local' symbol property to distinguish function-local symbols

Parameters have a 'child' relation to their function/method.
Also add an option '-include-locals' to 'c-index-test core' to enable indexing of function-local symbols.

Original patch from Nathan Hawes with some changes by me.
https://reviews.llvm.org/D30304

llvm-svn: 296282
diff --git a/clang/lib/Index/IndexBody.cpp b/clang/lib/Index/IndexBody.cpp
index 3aa0152..7681de7 100644
--- a/clang/lib/Index/IndexBody.cpp
+++ b/clang/lib/Index/IndexBody.cpp
@@ -269,7 +269,7 @@
       const Decl *D = *I;
       if (!D)
         continue;
-      if (!IndexCtx.isFunctionLocalDecl(D))
+      if (!isFunctionLocalSymbol(D))
         IndexCtx.indexTopLevelDecl(D);
     }