gnu: ungoogled-chromium: Update to 80.0.3987.116-0.bb952f1.

gnu: ungoogled-chromium: Update to 80.0.3987.116-0.bb952f1.

* gnu/packages/chromium.scm (%preserved-third-party-files): Adjust for
Chromium 80.
(%chromium-version): Set to 80.0.3987.116.
(%ungoogled-revision): Set to bb952f18c8c80c569583edd8dbb0b54443f49043.
(%debian-revision): Set to debian/80.0.3987.116-1.
(%chromium-origin, %ungoogled-origin, %debian-origin): Update hashes.
(ungoogled-chromium)[arguments]: In #:configure-flags, add "is_cfi=false".
Remove "is_clang", "enable_iterator_debugging", "exclude_unwind_tables",
"use_jumbo_build", "jumbo_file_merge_limit".  Adjust environment for building
with Clang.
[native-inputs]: Remove GCC-8.  Add CLANG-9 and LD-WRAPPER-NEXT.