This change suppresses results from "Declaration hides parameter" where
the ParameterDeclarationEntry does not link up to the right
FunctionDeclarationEntry.
Bad magic ended up in `LocalVariable.getFunction` and effectively
created a Cartesian product. Before this change, the timing looked like
this:
Variable::LocalVariable::getFunction_dispred#bb ... 50.1s
#select#cpe#123#fff ............................... 20.6s
After this change, those predicates become much faster:
Variable::LocalVariable::getFunction_dispred#ff ... 121ms
DeclarationHidesParameter::localVariableNames#fff . 77ms
#select#cpe#123#fff ............................... 28ms
Introducing the predicate `localVariableNames` ensures that we can do
the main join on two columns simultaneously, so that's a change we
should keep even if we remove the `pragma[nomagic]` later.
