mips: wrong -Werror=maybe-uninitialized warnings #4564

Job	Run time
mips32-big-endian	9m 0s
linux-cmake	3m 55s
macOS	6m 20s
linux (CFLAGS="-O1 -fno-omit-frame-pointer -fsanitize=address -fno-var-tracking" --disable-bindin...	2m 47s
mingw	29m 44s
linux (CC="clang")	2m 48s
mingw-cmake	6m 0s
linux (--enable-release)	2m 27s
ppc64-big-endian	9m 54s
linux (--enable-gcov --disable-bindings --disable-docs CFLAGS="-O0 -g")	2m 48s
vs2019	5m 21s
vs2019-ninja	4m 35s
linux (--disable-write --disable-docs)	2m 48s
linux (CFLAGS="-O2 -m32" --disable-bindings --disable-docs)	2m 45s
linux (CFLAGS="-O2 -fno-omit-frame-pointer -fsanitize=undefined -fno-var-tracking" --disable-bind...	2m 50s
	1h 34m 2s

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