submodules: update clippy from 9d33731 to 5afdf8b

Changes:

````
fix for rustc master
mem_forget: fix syntax error in code sample
explicit_counter_loop fix rust-lang#3308 false positive
new_ret_no_self test remove tool lints cfg flag
Added new_ret_no_self exception to clippy to pass dogfood tests
Removed new_ret_no_self tests from method.rs
new_ret_no_self correctly lint impl return
Removed unused variables
new_ret_no_self fix false positive for impl trait return with associated type self
new_ret_no_self corrected panic and added test stderr
new_ret_no_self added positive test cases
Fix some more `stutter` warnings
unused unit lint
Install Windows SDK 10.0 on travis
cmp_owned refactor
cmp_owned correct error message if rhs is deref
Add a comment reminding to update README if the default changes
Specify which categories are enabled by default
Only run markdown linter on linux
Move Travis Windows build to allowed failures
Add Travis windows build
Fix `doc_markdown` lints
Fix `stutter` lints
Fix `similar_names` warnings
cmp_owned current suggestion for multiple deref
cmp_owned add test for multiple dereference
Corrected single-character string constant used as pattern found in dogfood test
Fixes 3289, cmp_owned wording and false positive
````

Author: matthiaskrgr