Fix duplicated initialization in tkMenubutton.c, unneeded type-cast i… #664

Job	Run time
build (gcc)	1m 42s
build (gcc, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 48s
build (gcc, --disable-shared)	1m 45s
test (gcc)	4m 7s
build (gcc, --disable-xft)	1m 47s
test (gcc, --disable-xft)	4m 13s
build (gcc, --disable-xss)	1m 39s
test (gcc, --enable-symbols)	4m 0s
build (gcc, --enable-symbols)	1m 38s
build (clang)	2m 6s
build (clang, CFLAGS=-DTK_NO_DEPRECATED=1)	2m 27s
build (clang, --disable-shared)	1m 48s
build (clang, --disable-xft)	2m 24s
build (clang, --disable-xss)	2m 11s
build (clang, --enable-symbols)	1m 28s
	35m 3s

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