cxxll::maybe: Fix access issue in from-compatible-maybe constructor
cxxll::dwarf_cu::range: Support version, low_pc, high_pc attributes
SQL schema: New columns version, low_pc, high_pc in DWARF units

This updates symboldb.dwarf_compilation_unit and its loading code.
symboldb integration test: Adjustments for DWARF changes
Add test RPMs that reveal the ELF cache ordering dependence
symboldb integration test: Stop after the first round of diff failures

This allows for easier application of the resulting patches.