[NFC] Fix hasQualifier comment (#90485)

operator bool from NestedNameSpecifierLoc and
member function hasQualifier both do the same thing, returning true if
the private data member Qualifier is not nullptr, so clearly one of the
comments is wrong, and in this case it is the second one.

fixes #90472

Author: sousajo-cc

clang/include/clang/AST/NestedNameSpecifier.h

@@ -266,7 +266,7 @@ class NestedNameSpecifierLoc {
   explicit operator bool() const { return Qualifier; }
 
   /// Evaluates true when this nested-name-specifier location is
-  /// empty.
+  /// non-empty.
   bool hasQualifier() const { return Qualifier; }
 
   /// Retrieve the nested-name-specifier to which this instance