Include internal dependency in extraHash computation

[Friendseeker]

Issue

PR #1289 addressed under-compilation for traits with transitive external inheritance dependencies by propagating TraitPrivateMembersModified from parent trait to child traits.

However, when the hierarchy consists a mix of internal & external dependencies, TraitPrivateMembersModified would fail to propagate, resulting in under compilation.

For example, say c.C -> b.B -> a.A, (c.C extends c.B, c.B extends a.A), for which c.C and c.B, a.A are on different projects, then when a.A 's private member is changed, the propagation stops at c.B since computation of c.B's extraHash only takes account of a.A's external dependency, while a.A is part of c.B's internal dependency. Hence c.C never gets recompiled.

Fix

Include internal dependency in extraHash computation.

[eed3si9n]

Thanks!