[RISCV] Fold PseudoVMV_V_V with undef passthru, handling policy (#106943)

If a vmv.v.v has an undef passthru then we can just replace it with its
input operand, since the tail is completely undefined.

This is a reattempt of #106840, but also checks to see if the input was
a pseudo where we can relax its tail policy to undef.

This also means we don't need to check for undef passthrus in
foldVMV_V_V anymore because they will be handled by
foldUndefPassthruVMV_V_V.

0 files changed, 0 insertions, 0 deletions