Forgot the following flags:`-L=-merge_zero_fill_sections -L=-no_exported_symbols -L=-no_eh_labels -L=-dead_strip_dylibs`
So the full command is: ```ldc2 --release --O3 --flto=full -fvisibility=hidden -defaultlib=phobos2-ldc-lto,druntime-ldc-lto -L=-dead_strip -L=-x -L=-S -L=-lz -L=-merge_zero_fill_sections -L=-no_exported_symbols -L=-no_eh_labels -L=-dead_strip_dylibs main.d
``` resulting in a executable of 588KB.
