Update git submodules

* Update prebuilts/clang/host/linux-x86 from branch 'master'
  to 8b0689df9225c41530631f9bd6d7703815f08ae7
  - Update README
    
    Test: N/A
    Change-Id: I331c8b3171258478e7cc0bda54d695cbfae11802
    
  - Remove unused clang-r437112b
    
    Test: presubmit
    Change-Id: If355cf5f0efdcfc3340802f5edaaabd7486dead0
    
1 file changed