Fix #14436 fuzzing crash (null-pointer-use) in getEnumType() (#8711)

Author: chrchr-github

lib/tokenlist.cpp

@@ -2005,7 +2005,7 @@ void TokenList::validateAst(bool print) const
             if (Token::simpleMatch(tok->previous(), "operator"))
                 continue;
             // Skip incomplete code
-            if (!tok->astOperand1() && !tok->astOperand2() && !tok->astParent())
+            if (!tok->astOperand1() && !tok->astOperand2() && !tok->astParent() && !(tok->str().size() == 2 && tok->str()[1] == '='))
                 continue;
             // Skip lambda assignment and/or initializer
             if (Token::Match(tok, "= {|^|["))

test/cli/fuzz-crash/crash-793c09dbb007b0e1a295f592813f40f8d6d449d1

@@ -0,0 +1 @@
+enum{A=s(u)0&=s};