use relative includes

[ChillerDragon]

ddnet/ddnet#10055 (comment)

ddnet_base/scripts/update.sh

Lines 43 to 49 in 5cc8eda

	sed -E 's/^#include "..\/(.*)"/#include <ddnet_base\/base\/\1>/' "$header_file" > "$header_file".tmp
	mv "$header_file".tmp "$header_file"
	fi
	# TODO: merging into one sed command is probably faster
	sed -E 's/^#include "(.*)"/#include <ddnet_base\/base\/\1>/' "$header_file" | \
	sed -E 's/^#include <base\/(.*)>/#include <ddnet_base\/base\/\1>/' > "$header_file".tmp