Fix linux build

[phurley67]

We are encountering a missing symbol error in Ubuntu 22.04 LTS.

irb(main):001:0>require 'jsonnet'
Traceback (most recent call last):
       13: from /home/parallels/.asdf/installs/ruby/2.7.5/bin/irb:23:in `<main>'
       12: from /home/parallels/.asdf/installs/ruby/2.7.5/bin/irb:23:in `load'
       11: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/gems/2.7.0/gems/irb-1.2.6/exe/irb:11:in `<top (required)>'
       10: from (irb):1
        9: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:147:in `require'
        8: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:158:in `rescue in require'
        7: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:158:in `require'
        6: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/gems/2.7.0/gems/jsonnet-0.5.0/lib/jsonnet.rb:2:in `<top (required)>'
        5: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:83:in `require'
        4: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:83:in `require'
        3: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/gems/2.7.0/gems/jsonnet-0.5.0/lib/jsonnet/vm.rb:1:in `<top (required)>'
        2: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:83:in `require'
        1: from /home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:83:in `require'
LoadError (/home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/gems/2.7.0/gems/jsonnet-0.5.0/lib/jsonnet/jsonnet_wrap.so: undefined symbol: _ZTVN10__cxxabiv117__class_type_infoE - 
/home/parallels/.asdf/installs/ruby/2.7.5/lib/ruby/gems/2.7.0/gems/jsonnet-0.5.0/lib/jsonnet/jsonnet_wrap.so)

$ruby -v
ruby 2.7.5p203 (2021-11-24 revision f69aeb8314) [aarch64-linux]

Did a bit of digging and _ZTVN10__cxxabiv117__class_type_infoE decodes as vtable for __cxxabiv1::__class_type_info so I assumed we were not linking some important C++ libraries. Changed the link command to use c++ rather than cc and it fixed the issue.

[yugui]

Thank you for the report and the fix. It looks good to me.

I added another commit on top of your change to improve compatibility.