Remove an unused restrict proc. #3475

Job	Run time
build (gcc)	1m 43s
build (gcc, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 44s
test (gcc)	4m 1s
build (gcc, --disable-shared)	1m 39s
test (gcc, --disable-xft)	4m 0s
build (gcc, --disable-xft)	1m 38s
test (gcc, --enable-symbols)	3m 51s
build (gcc, --disable-xss)	1m 43s
build (gcc, --enable-symbols)	1m 19s
build (clang)	2m 19s
build (clang, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 55s
build (clang, --disable-shared)	2m 9s
build (clang, --disable-xft)	1m 54s
build (clang, --disable-xss)	1m 54s
build (clang, --enable-symbols)	1m 22s
	33m 11s

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