Reuse PropList-2.1.2 for Unicode 2.1.5

The Unicode 2.1.5 update did not ship a PropList, so the 2.1.2 file still
applied, but the resources left 2.1.5 without binary properties. Reuse
it the same way 2.1.5 already reuses the Unicode 2.0 blocks file.

Assisted-By: Claude Opus 5.5

Author: JLHwung