build.zig: blank out "*test.zig" files instead of omit

Now that `@import` of a non-existent file name is a compile error, the
Zig installation needs to include files that end with test.zig. However
we still want to avoid bloat in the installation size, so we blank them
out instead of omitting them entirely.

Now AstGen of the full standard library can complete successfully on a
Zig installation rather than erroring out with file not found.

0 files changed, 0 insertions, 0 deletions