Use apt clang instead of manually installing clang

[mschwager]

Using -lstdc++ fixes issues like:

$ ruby -e 'require "ruzzy"; print Ruzzy::ASAN_PATH'
<internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb>:85:in `require': /var/lib/gems/3.1.0/gems/ruzzy-0.6.0/lib/cruzzy/cruzzy.so: undefined symbol: _ZNSt6thread6_StateD2Ev - /var/lib/gems/3.1.0/gems/ruzzy-0.6.0/lib/cruzzy/cruzzy.so (LoadError)
	from <internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from /var/lib/gems/3.1.0/gems/ruzzy-0.6.0/lib/ruzzy.rb:7:in `<module:Ruzzy>'
	from /var/lib/gems/3.1.0/gems/ruzzy-0.6.0/lib/ruzzy.rb:6:in `<top (required)>'
	from <internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb>:160:in `require'
	from <internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb>:160:in `rescue in require'
	from <internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb>:149:in `require'
	from -e:1:in `<main>'
<internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb>:85:in `require': cannot load such file -- ruzzy (LoadError)
	from <internal:/usr/lib/ruby/vendor_ruby/rubygems/core_ext/kernel_require.rb>:85:in `require'
	from -e:1:in `<main>'

Changing the dummy code was necessary because older versions of clang do not set detect_stack_use_after_return=1 by default. Instead of adding this to the environment, I decided to use different ASAN violation code so we don't require ASAN_OPTIONS modification.

There's some debate as to whether we should use -lstdc++ or -lc++. I'm not sure what the right answer is, but -lstdc++ works for me while -lc++ doesn't. These links may help give some context or recommendations:

• https://reviews.llvm.org/D84947
• https://reviews.llvm.org/D85339
• https://reviews.llvm.org/D37631
• https://github.com/google/atheris/blob/2.3.0/libfuzzer_mod/cpython-3.8.6-add-libFuzzer.patch

[AdvenamTacet]

I'm going to check it Tomorrow, but based on reading without running, LGTM.

[AdvenamTacet]

LGTM, I want to suggest future changes, but I can do it in another PR. Those changes fix the issue we know.
I didn't find any new problem after applying that PR.

There's some debate as to whether we should use -lstdc++ or -lc++. I'm not sure what the right answer is, but -lstdc++ works for me while -lc++ doesn't. These links may help give some context or recommendations:

I was able to compile with with libc++, so it should work as well, but I can look at it later. If there is no reason to not use libc++, I think it's better to use libc++.