fix Issue 14828 - duplicate symbol __ModuleInfoZ

[MartinNowak]

• always emit __arrayZ/__assertZ/__unittest_failZ helpers (even in release)
  to avoid linkage issues when instantiating a template of that module
  with different compiler flags
• also fixes Issue 14748 - Removing std.stdio import causes 2x increase in "Hello, world"
  same underlying issue, some undefined helper function drag in a different
  module which happens to have weak definitions of those helpers

Issue 14828 – [REG2.067] duplicate symbol __ModuleInfoZ depending on ordering of files passed to dmd

[WalterBright]

LGTM

When making PR's that fix a bugzilla issue, please include a link to the issue, such as https://issues.dlang.org/show_bug.cgi?id=14828

[WalterBright]

Also should reference other PRs that address the same issue - #3552 and #4851

[MartinNowak]

When making PR's that fix a bugzilla issue, please include a link to the issue, such as https://issues.dlang.org/show_bug.cgi?id=14828

I usually do, it was a little late yesterday.

[rainers]

If it is actually ok to require deimos-like modules to be compiled, too, maybe we can resurrect #3958 to get proper TypeInfo for structs.

A lot of work has been done to avoid compilation of these files (by trying to guess what TypeInfo the backend will require, not completely successful so far), switching to a simpler compilation model would avoid all these complications.

[MartinNowak]

If it is actually ok to require deimos-like modules to be compiled, too, maybe we can resurrect #3958 to get proper TypeInfo for structs.

This is not what we decided. You'll almost never need an __arrayZ or __assertZ helper in deimos (b/c there are no D arrays in C, and rarely asserts in headers), and you could still workaround needing them.

Compiling headers with zero initialized structs is quite a bummer. Let's discuss #3958 together with overhauling the template instantiation implementation (see #4784, and #4780 (comment)).