Use return pointers from fromConstInitializer in CmpExp-visitor

Went missing after refactoring operation in 0215b469. Instead input
argument e member variables e1/e2 were used.
Merge pull request #3619 from andron/visitor-refactor-fix

Visitor refactor fix
[Refactoring] checkPurity, checkSafety, and checkNogc
[Refactoring] Add FuncDeclaration::isPureBypassingInferenceX()
fix Issue 6359 - Pure/@safe-inference should not be affected by __traits(compiles)
+fix indent
+9148_a add pure attribute for nested functions in a pure function
+9148_b calling function pointer/delegate that comes from paramter should be weak purity
+9148_c Passing impure delegate in the parameter of weak purity function call should check whole call-expr purity
+9148_d +y (disable member functions)
Fix regression caused by 10329? - comes from 6359
improve purity more
Remove hack for issue 10981
Inherit @safe and pure attributes to nested symbols
fix test cases
-keep backward compatibility
X
+rebased on fix6359
fix 6359
+