Fix tests.

Author: someone-with-default-username

Nitra/Nitra.Grammar/NitraSyntax.nitra

@@ -1883,7 +1883,7 @@ syntax module NitraSyntax : NitraLang
               if (RuleMethodBody.IsEmpty())
               {
                 unless (ruleSymbol is ExtensibleRuleSymbol)
-                  compilerMessages.Error(this, "An abstract rule method must be defined in an extension point rule only.");
+                  compilerMessages.Error(this, "An abstract rule method must be defined in an extensible rule only.");
                 RuleMethod.ParsedAbstractSymbol(this)
               }
               else

Tests/!Negative/RestrictedNames.nitra

@@ -6,7 +6,7 @@
   {
     | A = "a"
     {
-      private GetHashCode() : int = 0; //E:Name 'GetHashCode' is restricted due to internal use
+      GetHashCode() : int = 0; //E:Name 'GetHashCode' is restricted due to internal use
     }
 
     | B = Location="b" //E:Name 'Location' is restricted due to internal use

Tests/!Negative/RuleMethod-1.nitra

@@ -4,18 +4,14 @@
 
   syntax X = "x"
   {
-    private Field1() : int; //E:A private rule method must have a body
-
-    Field2() : int; //E:An abstract rule method must be defined in an extension point rule only
+    Field2() : int; //E:An abstract rule method must be defined in an extensible rule only
   }
 
   syntax Y
   {
-    private Field1() : int; //E:A private rule method can be declared only in simple rules and extension rules
-
     | Z = "z"
       {
-        Field2() : int = 0; //E:A public rule method must be defined in an extension point rule or a simple rule only
+        Field2() : int; //E:An abstract rule method must be defined in an extensible rule only
       }
   }
 }