hg: jdk10/sandbox: Properly filter out duplicate source files

[erik.joelsson at oracle.com]

Changeset: e2bfae7d74f3
Author:    erikj
Date:      2017-04-04 16:42 +0200
URL:       http://hg.openjdk.java.net/jdk10/sandbox/rev/e2bfae7d74f3

Properly filter out duplicate source files

! make/common/MakeBase.gmk
! make/common/NativeCompilation.gmk
! test/make/TestMakeBase.gmk