[MIR] Teach the printer how to print complex types for generic machine instructions.

Before this change, we would get the type definition in the middle
of the instruction.
E.g., %0(48) = G_ADD %struct_alias = type { i32, i16 } %edi, %edi

Now, we have just the expected type name:
%0(48) = G_ADD %struct_alias %edi, %edi

llvm-svn: 262885