C++: Remove NoThrowAllocator and inline its (corrected) definition in ThrowingAllocator.

Author: MathiasVP

cpp/ql/src/experimental/Security/CWE/CWE-570/IncorrectAllocationErrorHandling.ql

@@ -147,21 +147,16 @@ predicate exprMayThrow(Expr e) {
   )
 }
 
-/** An allocator that will not throw an exception. */
-class NoThrowAllocator extends Function {
-  NoThrowAllocator() {
+/** An allocator that might throw an exception. */
+class ThrowingAllocator extends Function {
+  ThrowingAllocator() {
     exists(NewOrNewArrayExpr newExpr |
       newExpr.getAllocator() = this and
-      not functionMayThrow(this)
+      functionMayThrow(this)
     )
   }
 }
 
-/** An allocator that might throw an exception. */
-class ThrowingAllocator extends Function {
-  ThrowingAllocator() { not this instanceof NoThrowAllocator }
-}
-
 /** The `std::bad_alloc` exception and its `bsl` variant. */
 class BadAllocType extends Class {
   BadAllocType() { this.hasGlobalOrStdOrBslName("bad_alloc") }