Fix #12629 fuzzing timeout in valueFlowSymbolicOperators() (#6328)

Author: chrchr-github

lib/symboldatabase.cpp

@@ -2055,6 +2055,8 @@ bool SymbolDatabase::isFunction(const Token *tok, const Scope* outerScope, const
 
     // template constructor?
     else if (Token::Match(tok, "%name% <") && Token::simpleMatch(tok->next()->link(), "> (")) {
+        if (tok->isKeyword() || tok->isStandardType() || !outerScope->isClassOrStructOrUnion())
+            return false;
         const Token* tok2 = tok->next()->link()->next()->link();
         if (Token::Match(tok2, ") const| ;|{|=") ||
             Token::Match(tok2, ") : ::| %name% (|::|<|{") ||

test/cli/fuzz-timeout/timeout-7795aa299fc0c2bafe3a152785d55b039d4f339c

@@ -0,0 +1 @@
+ e<>(){F+0+0+++++++++++++++++++++++++++++++++++++++++5;}

test/testgarbage.cpp

@@ -907,7 +907,6 @@ class TestGarbage : public TestFixture {
 
     void garbageCode109() { //  #6900 "segmentation fault (invalid code) in CheckStl::runSimplifiedChecks"
         checkCode("( *const<> (( ) ) { } ( *const ( ) ( ) ) { } ( * const<> ( size_t )) ) { } ( * const ( ) ( ) ) { }");
-        ignore_errout(); // we do not care about the output
     }
 
     void garbageCode110() { //  #6902 "segmentation fault (invalid code) in CheckStl::string_c_str"