(1) Makefile
  convert pre-configure: target to fix following:
autoreconf: running: aclocal --force -I m4
aclocal: warning: autoconf input should be named 'configure.ac', not 'configure.in'
aclocal: error: couldn't open directory 'm4': No such file or directory
autoreconf: aclocal failed with exit status: 1
*** Error code 1

(2) patches/patch-configure.in
Add more chunk to fix following:
configure.in:2: error: 'AM_CONFIG_HEADER': this macro is obsolete.
    You should use the 'AC_CONFIG_HEADERS' macro instead.
/usr/pkg/share/aclocal-1.13/obsolete-err.m4:12: AM_CONFIG_HEADER is expanded from...
configure.in:2: the top level
autom4te: /usr/pkg/bin/gm4 failed with exit status: 1

(Checked (only) on NetBSD/amd64 6.1.3), thanks a lot.