fig_19, tab_04: `prepare.sh`'s `lib_src.zip` is missing

[n0toose]

prepare.sh downloads lib_src.zip from https://vmx.cs.pub.ro/~vmchecker/lib_src.zip - no backup domain was included:

eurosys21-artifacts/experiments/fig_19_compare-dpdk/prepare.sh

Lines 1 to 5 in d88853d

	# get dpdk
	cd aux
	wget http://vmx.cs.pub.ro/~vmchecker/lib_src.zip
	unzip lib_src
	rm lib_src.zip

http://vmx.cs.pub.ro is a "Shell-in-a-Box" service - the file is not available on there anymore. lib_src's name is generic enough to the point where it's not easy to tell what that file is supposed to do or where it comes from.

Figure 19 (DPDK) is therefore not possible to reproduce.