Verilator and Icarus from extracted .debs: the path fixes they need

Both run without root after dpkg-deb -x pkg.deb root (Ubuntu noble verilator 5.020, iverilog 12.0), but each needs a path fix. Icarus: the iverilog driver looks for ivl/ivlpp in a wrong relocated directory ($R/usr/x86_64-linux-gnu/ivl, without lib), so pass iverilog -B $R/usr/lib/x86_64-linux-gnu/ivl ...; vvp then runs the output with no extra flags. Verilator: set VERILATOR_ROOT=$R/usr/share/verilator and put $R/usr/bin on PATH. The perl wrapper still execs $VERILATOR_ROOT/verilator_bin ('exec: ... verilator_bin: not found'), so symlink verilator_bin and verilator_bin_dbg from usr/bin into that directory. After that, verilator --binary --timing t.sv builds with the system g++/make.