tools/clean-svg: ignore an empty Layout= line #1205

Job	Run time
valgrind	2m 58s
build-and-dist (gcc)	1m 1s
build-and-dist (gcc, -Db_sanitize=address,undefined -Db_lundef=false)	44s
build-and-dist (clang)	46s
build-and-dist (clang, -Db_sanitize=address,undefined -Db_lundef=false)	46s
clean-svg-check	28s
build-from-tarball	2m 36s
duplicate-devices	33s
etcdir (sudo mv /usr/share/libwacom/wacom-intuos*.tablet /etc/libwacom)	30s
etcdir (sudo mv /usr/share/libwacom/*.tablet /etc/libwacom)	33s
etcdir (sudo mv /usr/share/libwacom/*.stylus /etc/libwacom)	27s
etcdir (sudo mv /usr/share/libwacom/*.tablet $HOME/.config/libwacom)	29s
etcdir (sudo mv /usr/share/libwacom/*.stylus $HOME/.config/libwacom)	31s
etcdir (sudo mv /usr/share/libwacom/wacom-*.tablet $HOME/.config/libwacom && sudo mv /usr/share/l...	1m 40s
etcdir (sudo csplit data/wacom.stylus '/^\[0x822\]/' && sudo mv xx00 /etc/libwacom/first.stylus &...	21s
	14m 23s

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