- libepoxy dlopen()s libEGL / libGL but didn't have mesa in its runpath
-> error unless lib is already open or in LD_LIBRARY_PATH
- change dependency from mesa (should be avoided) to mesa_nonglu
The most complex problems were from dealing with switches reverted in
the meantime (gcc5, gmp6, ncurses6).
It's likely that darwin is (still) broken nontrivially.