Support --with-cxx option

[youpong]

Description

Add following options and environment variable to configure script:

Options:

• --with-cxx=CXX use CXX to compile
• -v, --version show version information

Environment variable:

• CXX C++ compiler command

Related Issue(s)

• Support LLVM/Clang++ #52

[codecov]

Codecov Report

Merging #133 (d8eabe8) into main (e9a357a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #133   +/-   ##
=======================================
  Coverage   29.49%   29.49%           
=======================================
  Files           4        4           
  Lines         512      512           
=======================================
  Hits          151      151           
  Misses        361      361           

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[youpong]

The current configure script is failing on macOS because it depends on GNU getopt(1).
Please postpone merging this pull request until we can resolve the issue on macOS.

[youpong]

Now, It's ready to merge.

• Install GNU Getopt(1) on macOS
• Modify configure script to be compliant with both macOS and Ubuntu.

[youpong]

Thunks!
Thanks!