AWT source dirs should only point to java2d, not below

This is from a code review following the jigsaw source file restructuring:

* The makefiles include too specific directories. Instead of including e.g. ./*/native/common/sun/java2d/opengl and ./*/native/common/sun/java2d/x11, we should just include ./*/native/common/sun/java2d. This level corresponds to a logical grouping of the source code, and not the directory structure in that grouping.