fn evalZigProcess(s: *Step, argv: []const []const u8, prog_node: *std.Progress.Node) !?[]const u8

Assumes that argv contains --listen=- and that the process being spawned is the zig compiler - the same version that compiled the build runner.

Parameters

s: *Step,
argv: []const []const u8,
prog_node: *std.Progress.Node,