provide default implementation of std.log on freestanding
provide default implementation of std.log on freestanding

closes #6252

zig-lang/zig,raulgrell/zig,raulgrell/zig,raulgrell/zig,andrewrk/zig,raulgrell/zig,andrewrk/zig,zig-lang/zig,zig-lang/zig,raulgrell/zig