Fix a bug with disappeared cast to byte in numeric binary expressions

Fix a bug with disappeared cast to byte in numeric binary expressions

Lowering::IndirsAreEquivalent doesn't check if the 2 indirections have the same type and because of that a RMW style instruction is generated instead of the expected

movzx    rax, byte  ptr [7FFA61024742h]
xor      eax, 33
mov      word  ptr [7FFA61024742h], ax

This behavior was fixed by adding an additional check to IndirsAreEquivalent (implementation of the mikedn's approach: https://github.com/dotnet/coreclr/pull/1329#discussion_r36397171).

Fix #1323.