dev-lang/ldc2::dlang: required -ffat-lto-objects

[mccarverone]

dev-lang/ldc2 is from dlang overlay. Requires -ffat-lto-objects to compile, otherwise it fails with lots of unrecognized symbols.

This is a compiler so it definitely requires further tests to ensure that everything works fine.

build.log

[Connor-GH]

Tested with 1.35. Works with clang -flto but not with gcc. Still needs -ffat-lto-objects.

[Connor-GH]

Considering I build and bootstrap ldc2 with itself and also build dmd with it and many personal projects, I would consider ldc2 fine to use with clang lto.