While at it making it as well kernel 5.4 compatible by backporting
upstream patch which synchronizes channel types and modifier lists in
the headers.

Signed-off-by: Petr Štetiar <ynezz@true.cz>

- remove upstreamed patch
- remove dependency to libavahi-common which does not exist,
  seems that I have confused library name vs package name (fixes #5480)
(- only compile tested at the moment)

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

On buildbots, the building directory seems to be not a subdir of
a git repo, so a variable expands into an empty string which in turn
results in a syntax error:

--snip--
  -- Looking for in6addr_any - found
  -- Found Git: /data/bowl-builder/arm_cortex-a5/build/sdk/staging_dir/host/bin/git (found version "2.1.4")
  fatal: Not a git repository (or any parent up to mount point /data)
  Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set).
  CMake Error at CMakeLists.txt:114 (if):
    if given arguments:

      "STREQUAL" "/data/bowl-builder/arm_cortex-a5/build/sdk/build_dir/target-arm_cortex-a5_musl_eabi/libiio-0.11"

    Unknown arguments specified

  -- Configuring incomplete, errors occurred!
--snap--

The patch quotes the if arguments and thus fixes the build.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>