Fixed errors

Added some new classes for built in operations that for the moment
have no effect (added to remove errors)

csharp/ql/src/semmle/code/csharp/ir/implementation/raw/internal/IRConstruction.qll

@@ -277,6 +277,10 @@ cached private module Cached {
       result = element.getPrimaryInstructionForSideEffect(tag)
     )
   }
+  
+  cached Language::BuiltInOperation getInstructionBuiltInOperation(Instruction instr) {
+    none() 
+  }
 }
 
 import CachedForDebugging

csharp/ql/src/semmle/code/csharp/ir/internal/IRCSharpLanguage.qll

@@ -17,6 +17,15 @@ private newtype TClassDerivation =
     derived.getABaseType() = base
   }
 
+private newtype TBuiltInOperation = 
+  NoOp()
+  
+class BuiltInOperation extends TBuiltInOperation {
+  string toString() {
+    result = "BuiltInOp"
+  }
+}
+  
 class ClassDerivation extends MkClassDerivation {
   Class baseClass;
   Class derivedClass;