make uninstall has wrong path

[tank-trax]

built on Debian 9

the install path is /usr/local/lib/lv2/

however the uninstall path is /usr/lib/lv2/

had to change line 66 of Makefile

from
-rm -rf $(DESTDIR)$(PREFIX)/lib/lv2/mod-caps-*.lv2/
to
-rm -rf $(DESTDIR)$(PREFIX)/local/lib/lv2/mod-caps-*.lv2/