restore useful compiler errors on dumb terminals

This reverts a part of 7cc4a69, and
closes ziglang#16376.

While the "correct" behavior on dumb terminals is still to be determined,
this is arguably a major regression from 0.10.0 to 0.11.0, leaving users
of various tools and CI platforms without any useful build logs.

This change mirrors the behavior of basically every other compiler out
there, which is to just not color the output (done implicitly in `std.io.tty`).

Of course, the idea for machine-readable compiler errors still has
merit, and with things like the to-be-implemented Zig compiler
server [0] and ZLS, there are just better ways to go about it than to
print somewhat useless error messages that a good portion of users will
see.

[0]: ziglang#615

lib/build_runner.zig

@@ -1064,7 +1064,5 @@ fn get_tty_conf(color: Color, stderr: std.fs.File) std.io.tty.Config {
 fn renderOptions(ttyconf: std.io.tty.Config) std.zig.ErrorBundle.RenderOptions {
     return .{
         .ttyconf = ttyconf,
-        .include_source_line = ttyconf != .no_color,
-        .include_reference_trace = ttyconf != .no_color,
     };
 }

src/main.zig

@@ -6369,8 +6369,6 @@ fn renderOptions(color: Color) std.zig.ErrorBundle.RenderOptions {
     const ttyconf = get_tty_conf(color);
     return .{
         .ttyconf = ttyconf,
-        .include_source_line = ttyconf != .no_color,
-        .include_reference_trace = ttyconf != .no_color,
     };
 }