cmake --build was invoked with no --parallel, so the default Unix
Makefiles generator compiled external deps (DPP, msquic, glslang, …)
one translation unit at a time, leaving all but one core idle.
Pass an explicit --parallel N using hardware_concurrency() so dep
builds use the available cores. An explicit count (not a bare
--parallel) avoids an unbounded make -j fork bomb on the Makefiles
generator.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
