Packaging cquery

[brettg]

Hi all, I am attempting to package cquery.

Here is my definition

(define-public cquery
  (package
   (name "cquery")
   (version "20180718")
   (source (origin
            (method url-fetch)
	    (uri (string-append 
"https://github.com/cquery-project/cquery/archive/v";
                                version ".tar.gz"))
            (sha256
             (base32
              "076cavgipn6g37fhvdcq0z915c5lxxa56mbxw9d6njksdxg1wdkj"))))
   (build-system cmake-build-system)
   (inputs
    `(("python" ,python-wrapper)
      ("clang" ,clang)))
   (home-page "https://github.com/cquery-project/cquery";)
   (synopsis "C/C++ language server supporting multi-million line code 
base, powered by libclang")
   (description "Add later.")
   (license license:x11-style)))

the configuration seems to fail when cmake attempts to download clang. 
Does anybody know how to get it to ignore this request and use the 
system clang (which I assume is the correct (guix) way to do this.

-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Using downloaded Clang
-- Downloading Clang 6.0.0 
(https://releases.llvm.org/6.0.0/clang+llvm-6.0.0-x86_64-linux-gnu-ubuntu-14.04.tar.xz) 
...
CMake Error at cmake/DownloadAndExtractClang.cmake:82 (message):
  SHA256 hash of downloaded Clang does not match expected hash.  Remove 
the
  build directory and try running CMake again.  If this keeps happening, 
file
  an issue to report the problem.
Call Stack (most recent call first):
  CMakeLists.txt:96 (download_and_extract_clang)

Thanks,
Brett Gilio