move masked_move* AVX2 implementation to util/arch/x86

diff --git a/src/util/masked_move.c b/src/util/arch/x86/masked_move.c
similarity index 100%
rename from src/util/masked_move.c
rename to src/util/arch/x86/masked_move.c

diff --git a/src/util/masked_move.h b/src/util/arch/x86/masked_move.h
similarity index 100%
rename from src/util/masked_move.h
rename to src/util/arch/x86/masked_move.h