Autotools build improvement -- to support OpenBSD

[mcuee]

• Automatically determine Autoconf package version from cmake package version #1663 (comment)

As of now, git main Autotools build last step failed under OpenBSD.

Warning: target ./libavrdude.a (prerequisite of: avrdude) does not have any command (BUG)
  CCLD     avrdude
cc: error: no such file or directory: './libavrdude.a'
*** Error 1 in . (Makefile:1043 'avrdude': @echo "  CCLD    " avrdude;/bin/sh ./libtool --silent --tag=CC    --mode=link cc -Wall -Wextra -W...)
*** Error 1 in . (Makefile:2820 'all-recursive': @fail=;  if (target_option=k; case ${target_option-} in  ?) ;;  *) echo "am__make_running_w...)
*** Error 2 in /home/mcuee/build/avrdude/src (Makefile:886 'all')

I have not looked into OpenBSD port to see how they build avrdude 6.3.
https://github.com/openbsd/ports/tree/master/devel/avrdude

[mcuee]

Close this one and merge this into Issue #1664.

• Autotools build improvement  #1664