[TwoAddressInstructionPass] Create register mapping for registers with...

[TwoAddressInstructionPass] Create register mapping for registers with multiple uses in the current MBB

Currently we create register mappings for registers used only once in current
MBB. For registers with multiple uses, when all the uses are in the current MBB,
we can also create mappings for them similarly according to the last use.
For example

    %reg101 = ...
            = ... reg101
    %reg103 = ADD %reg101, %reg102

We can create mapping between %reg101 and %reg103.

Differential Revision: https://reviews.llvm.org/D113193