Fix BLOCKSTRETCHACTION object codes #4652

Job	Run time
macOS	8m 11s
linux (CFLAGS="-O1 -fno-omit-frame-pointer -fsanitize=address -fno-var-tracking" --disable-bindin...	8m 8s
mingw	8m 0s
linux (CC="clang")	8m 9s
mingw-cmake	7m 11s
linux (--enable-release)	8m 7s
linux (--enable-gcov --disable-bindings --disable-docs CFLAGS="-O0 -g")	8m 8s
ppc64-big-endian	8m 9s
linux (--disable-write --disable-docs)	8m 8s
vs2019	5m 33s
linux (CFLAGS="-O2 -m32" --disable-bindings --disable-docs)	8m 9s
linux (CFLAGS="-O2 -fno-omit-frame-pointer -fsanitize=undefined -fno-var-tracking" --disable-bind...	8m 8s
vs2019-ninja	4m 31s
linux-cmake	5m 56s
mips32-big-endian	8m 8s
	1h 52m 36s

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