[clang] [analyzer] Fix format attribute handling in GenericTaintChecker (PR #132765)

[Donát Nagy via cfe-commits]

================
@@ -161,3 +161,45 @@ void top() {
   clang_analyzer_isTainted(A.data); // expected-warning {{YES}}
 }
 } // namespace gh114270
+
+
+namespace format_attribute {
+__attribute__((__format__ (__printf__, 1, 2)))
+void log_nonmethod(const char *fmt, ...);
+
+void test_format_attribute_nonmethod() {
+  int n;
+  fscanf(stdin, "%d", &n); // Get a tainted value.
+                           
+  log_nonmethod("This number is suspicious: %d\n", n); // no-warning
+}
----------------
NagyDonat wrote:

```suggestion
void log_freefunc(const char *fmt, ...);

void test_format_attribute_freefunc() {
  int n;
  fscanf(stdin, "%d", &n); // Get a tainted value.
                           
  log_freefunc("This number is suspicious: %d\n", n); // no-warning
}
```

https://github.com/llvm/llvm-project/pull/132765