$ makepkg -As
==> Making package: mediatomb 0.12.1-15 (Sun Feb 17 20:14:48 2019)
==> Checking runtime dependencies...
==> Checking buildtime dependencies...
==> Retrieving sources...
  -> Found mediatomb-0.12.1.tar.gz
  -> Found mediatomb.sysusers
  -> Found mediatomb.service
  -> Found mediatomb-mariadb.service
  -> Found mediatomb.conf
  -> Found gcc46.patch
  -> Found tonewjs.patch
  -> Found jsparse.patch
  -> Found libav_0.7_support.patch
  -> Found libmp4v2_191_p497.patch
  -> Found libavformat.patch
  -> Found symlinks.patch
  -> Found truncated_auxdata.patch
==> Validating source files with sha256sums...
    mediatomb-0.12.1.tar.gz ... Passed
    mediatomb.sysusers ... Passed
    mediatomb.service ... Passed
    mediatomb-mariadb.service ... Passed
    mediatomb.conf ... Passed
    gcc46.patch ... Passed
    tonewjs.patch ... Passed
    jsparse.patch ... Passed
    libav_0.7_support.patch ... Passed
    libmp4v2_191_p497.patch ... Passed
    libavformat.patch ... Passed
    symlinks.patch ... Passed
    truncated_auxdata.patch ... Passed
==> Extracting sources...
  -> Extracting mediatomb-0.12.1.tar.gz with bsdtar
==> Starting prepare()...
patching file src/zmm/object.h
patching file build/Makefile.in
patching file src/scripting/import_script.cc
patching file src/scripting/js_functions.cc
patching file src/scripting/js_functions.h
patching file src/scripting/playlist_parser_script.cc
patching file src/scripting/script.cc
patching file src/scripting/script.h
patching file configure
patching file src/scripting/js_functions.cc
patching file src/metadata/ffmpeg_handler.cc
patching file src/metadata/libmp4v2_handler.cc
patching file src/metadata/ffmpeg_handler.cc
Hunk #2 succeeded at 279 (offset 1 line).
Hunk #3 succeeded at 287 (offset 1 line).
Hunk #4 succeeded at 304 (offset 1 line).
(Stripping trailing CRs from patch; use --binary to disable.)
patching file src/autoscan_inotify.cc
(Stripping trailing CRs from patch; use --binary to disable.)
patching file src/content_manager.cc
Hunk #1 succeeded at 202 with fuzz 1.
patching file src/metadata/taglib_handler.cc
==> Removing existing $pkgdir/ directory...
==> Starting build()...
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /usr/bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking build system type... configure_aux/config.guess: unable to guess system type

This script, last modified 2009-11-20, has failed to recognize
the operating system you are using. It is advised that you
download the most up to date version of the config scripts from

  http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD
and
  http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD

If the version you run (configure_aux/config.guess) is already up to date, please
send the following data and any information you think might be
pertinent to <config-patches@gnu.org> in order to provide the needed
information to handle your system.

config.guess timestamp = 2009-11-20

uname -m = aarch64
uname -r = 4.20.10-1-ARCH
uname -s = Linux
uname -v = #1 SMP PREEMPT Fri Feb 15 18:12:49 MST 2019

/usr/bin/uname -p = unknown
/bin/uname -X     =

hostinfo               =
/bin/universe          =
/usr/bin/arch -k       =
/bin/arch              =
/usr/bin/oslevel       =
/usr/convex/getsysinfo =

UNAME_MACHINE = aarch64
UNAME_RELEASE = 4.20.10-1-ARCH
UNAME_SYSTEM  = Linux
UNAME_VERSION = #1 SMP PREEMPT Fri Feb 15 18:12:49 MST 2019
configure: error: cannot guess build type; you must specify one
==> ERROR: A failure occurred in build().
    Aborting...