ART: Fix dependencies of dump-oat-core-target .

This was probably broken by
    https://android-review.googlesource.com/209369
which removed the "default" compiler type but didn't
uptate the variable names to those introduced in
    https://android-review.googlesource.com/337923 .

Test: m dump-oat-core-target
Change-Id: I0fad9a78fea13bf9c7da24d69bb217a2bc57257e