>>284
これか？やっと再現したわ。

libtoolize: Consider adding 'AC_CONFIG_MACRO_DIRS([m4])' to configure.ac,
libtoolize: and rerunning libtoolize and aclocal.
libtoolize: Consider adding '-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
configure.ac:94: error: possibly undefined macro: AC_MSG_WARN
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
autoreconf: /usr/bin/autoconf failed with exit status: 1

PKGBUILDのせいじゃなくて環境のせいだ。なんにせよ解決したらまた書き込む。