Fix [121786c0]: image svg upstream out of bound read nanosvg#262 #1246

Job	Run time
build (gcc)	1m 41s
test (gcc)	4m 51s
build (gcc, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 50s
test (gcc, --disable-xft)	4m 6s
build (gcc, --disable-shared)	1m 41s
test (gcc, --enable-symbols)	3m 33s
build (gcc, --disable-xft)	1m 51s
build (gcc, --disable-xss)	1m 43s
build (gcc, --enable-symbols)	2m 0s
build (clang)	1m 49s
build (clang, CFLAGS=-DTK_NO_DEPRECATED=1)	2m 30s
build (clang, --disable-shared)	1m 57s
build (clang, --disable-xft)	1m 53s
build (clang, --disable-xss)	1m 58s
build (clang, --enable-symbols)	1m 33s
	34m 56s

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