Fix endianness.asm

[nibblerenush]

Compiling the code in this file results in a "Segmentation fault (core dumped)" error:

nasm -felf64 ./endianness.asm -o endianness.o && ld -o endianness ./endianness.o
./endianness
Segmentation fault (core dumped)

After fix:

nasm -felf64 ./endianness.asm -o endianness.o && ld -o endianness ./endianness.o
./endianness
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