silence compiler warning #609

Job	Run time
build (gcc)	1m 38s
test (gcc)	4m 5s
build (gcc, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 42s
test (gcc, --disable-xft)	4m 3s
build (gcc, --disable-shared)	1m 39s
test (gcc, --enable-symbols)	3m 48s
build (gcc, --disable-xft)	1m 44s
build (gcc, --disable-xss)	1m 39s
build (gcc, --enable-symbols)	1m 13s
build (clang)	1m 48s
build (clang, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 51s
build (clang, --disable-shared)	2m 14s
build (clang, --disable-xft)	1m 54s
build (clang, --disable-xss)	2m 7s
build (clang, --enable-symbols)	1m 24s
	32m 49s

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