I got this error when building libvmod-re2

+ aclocal -I m4 -I /usr/share/aclocal
+ libtoolize --copy --force
libtoolize: putting auxiliary files in `.'.
libtoolize: copying file `./ltmain.sh'
libtoolize: putting macros in AC_CONFIG_MACRO_DIR, `m4'.
libtoolize: copying file `m4/libtool.m4'
libtoolize: copying file `m4/ltoptions.m4'
libtoolize: copying file `m4/ltsugar.m4'
libtoolize: copying file `m4/ltversion.m4'
libtoolize: copying file `m4/lt~obsolete.m4'
+ autoheader
+ automake --add-missing --copy --foreign
configure.ac:14: installing './compile'
configure.ac:9: installing './config.guess'
configure.ac:9: installing './config.sub'
configure.ac:12: installing './install-sh'
configure.ac:12: installing './missing'
src/Makefile.am: installing './depcomp'
+ autoconf
configure.ac:5: error: possibly undefined macro: AC_MSG_ERROR
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.

Some people saying it's because pkg-config wasn't installed. But I did have pkg-config installed in my system.