Clarify a few diagnostics so that they are more consistent with the
corresponding condition. For example:
if (positionAttr.size() > static_cast<unsigned>(getSourceVectorType().getRank()))
should lead to ("no greater than"):
return emitOpError( "expected position attribute of rank no greater than vector rank");
as opposed to ("smaller"):
return emitOpError( "expected position attribute of rank smaller than vector rank");