Ensure that sdk/module_exports depends on source members

Previously, preferring a prebuilt of an sdk/module_exports's member
would cause the sdk/module_exports to depend on the prebuilt instead
of the source and cause problems with the build.

This chance prevents the dependency from an sdk/module_exports to its
members from being replaced with prebuilts.

Bug: 160785918
Test: m nothing
Change-Id: Iee4bcd438c11929e30fb5766701b05a0e89956d9