emulators/ppsspp: update to 1.7.2 (nop)

No changes affect desktop Unix. Mainly to avoid portscout and repology
reporting the port as out of date.

Changes: http://ppsspp.org/#news
Changes: https://github.com/hrydgard/ppsspp/compare/v1.7.1...v1.7.2
MFH: 2018Q4 (aid future MFHs)