Fix constParameterPointer regression

Commit 7325154 ("Fix #11842 FN constParameterPointer with library function
(#5257)") most likely introduced a regression for (C) function pointers passed
to functions provided by the standard library that cppcheck has knowledge about.

lib/checkother.cpp

@@ -1560,6 +1560,13 @@ static const Token* getVariableChangedStart(const Variable* p)
     return start;
 }
 
+static bool isFunctionPointer(const Token *tok)
+{
+    if (!tok || !tok->next())
+        return false;
+    return Token::Match(tok->next(), "( * %var% )");
+}
+
 void CheckOther::checkConstPointer()
 {
     if (!mSettings->severity.isEnabled(Severity::style))
@@ -1660,7 +1667,7 @@ void CheckOther::checkConstPointer()
                                 continue;
                         }
                     }
-                } else {
+                } else if (!isFunctionPointer(var->typeStartToken())) {
                     const auto dir = mSettings->library.getArgDirection(ftok, argn + 1);
                     if (dir == Library::ArgumentChecks::Direction::DIR_IN)
                         continue;

test/testother.cpp

@@ -3808,6 +3808,12 @@ class TestOther : public TestFixture {
               "}\n");
         ASSERT_EQUALS("[test.cpp:1]: (style) Parameter 'p' can be declared as pointer to const\n",
                       errout.str());
+
+        check("void f(void *p, size_t nmemb, size_t size, int (*cmp)(const void *, const void *)) {\n"
+              "    qsort(p, nmemb, size, cmp);\n"
+              "}\n");
+        ASSERT_EQUALS("",
+                      errout.str());
     }
 
     void switchRedundantAssignmentTest() {