[index] Add 'Parameter' symbol kind and 'Local' symbol property to distinguish...

[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