[Issue 24320] Change std.writefln() into a regular variadic function not a template

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24320

--- Comment #3 from Walter Bright <bugzilla at digitalmars.com> ---
The build system, of course, will merge identical template instantiations. But
the purpose of templates is to provide specializations for their specific
arguments, and so they are different and cannot be merged. writefln() can
easily create hundreds of slightly different template instantiations, none of
which can be merged.

--