Add a pending test for sbt/sbt#1142

Add a scripted test documents the current behavior of incremental
compiler when it comes to handling of inherited macros. A whitespace
change to a file that inherits a macro triggers recompilation of all files that
depend (by composition or inheritance) on that file.
Classes that only inherit a macro don't have a macro

Prior to this commit, a class that inherited a macro from another
class was considered by incremental compiler as having a macro.
Now, only classes that explicitly define a macro are considered as having
a macro. This influences decision whether to invalidate (recompile)
dependencies of a file that inherits a macro upon a whitespace change.
From now on, we don't invalidate dependencies in such case which
results in much better incremental compiler experience when macros are
being involved. Check #1142 for detailed discussion.

The change to the behavior is reflected by marking the
source-dependencies/inherited-macros test as passing.
The source-dependencies/macro test covers the case of defining the macro
directly in source file. Therefore we know that the desired behavior of
invalidating dependencies of macros is preserved.

Fixes #1142
Merge pull request #1202 from Duhemm/inherited-macros

Disable macro heuristic for inherited macros (sbt/sbt#1142)