devel/lua-cqueues: adapt to the needs of dns/knot-resolver

• PORTDOCS / PORTEXAMPLES obviate the need to put docs and examples in the plist.
• There should be no messing with ldconfig and soname, since the .so exists only to be dynamically loaded at runtime, not actually linked to.
• Fixed name in the COMMENT
• Does not build on lua 5.4, note this in USES
• Force the port to build exactly the version it's supposed to build, rather than let it autodetect things. Hence MAKE_ENV and CPPFLAGS
• shebangfix on the examples is not strictly necessary but is cleaner.

PR: 247739
Submitted by: andrew@tao11.riddles.org.uk
Approved by: Leo Vandewoestijne <freebsd@dns.company> (maintainer)