Update git submodules

* Update tools/repohooks from branch 'master'
  to ce8e83897bc09f64b0523328e61b86902aa015ef
  - pre-upload: use first-parent diff for list of affected files
    
    Otherwise, trying to upload a merge can fail with errors like
    
     ValueError: Failed to parse diff output: ::100644 100644 100644 4d2b33a 4d2b33a d63fea7 MM      BUILD
    
    because "git diff <foo>^!" returns a diff against all parents
    that DIFF_RE does not know how to parse.
    
    Reported-by: Matthew Maurer <mmaurer@google.com>
    Change-Id: Iafd846f083c0c078b383f7d48ad00cce896a404c
    
1 file changed