message: Update README.md
  Remove sparsehash build section.
diff: @@ -32,11 +32,6 @@ in the `vscode-client` folder.
  # Build cquery
  $ git clone https://github.com/jacobdufault/cquery --recursive
  $ cd cquery
  -# Note: In the future we should not have to build sparsehash explicitly.
  -$ pushd third_party/sparsehash
  -$ ./configure
  -$ make
  -$ popd
  $ ./waf configure
  $ ./waf build
  