spectrum: Remove default virtual destructor from SimpleRefCount children
We have seen the same issue with MatrixArray in #995 (closed).
Fix #1088 (closed), #1089 (closed)
Also adding a new per-commit clang CI job to catch libc++ regressions (such as the one that popped up on MacOS being fixed in !1988 (merged)). Moved to a new MR.
Edited by Gabriel Ferreira