Revert unnecessary change in MV call to checkRuleResultList().

Due to a misreading of the function's comment block, there was an
unneeded change to a call in rewriteDefine.c.  There is, in fact
no reason to pass false for a MV; it should be true just like a
view.

Fixes issue pointed out by Tom Lane
Avoid inserting no-op Limit plan nodes.

This was discussed in connection with the patch to avoid inserting no-op
Result nodes, but not actually implemented therein.