Prevent revisiting block when searching for noreturn vars

When searching for noreturn variable initializations, do not visit CFG
blocks that are already visited, it prevents hanging  the analysis.

It must fix llvm#150336.

Upstream-Status: Submitted [llvm#150582]
Signed-off-by: Khem Raj <[email protected]>

Author: spavloff

clang/test/SemaCXX/noreturn-vars.cpp

@@ -225,3 +225,20 @@ extern void abc_02(func_type *);
   abc_02(&func_ptr);
   func_ptr();
 } // expected-warning {{function declared 'noreturn' should not return}}
+
+namespace Issue150336 {
+void free(void *);
+typedef void (*sel_freefunc)(void *);
+struct gmx_ana_selmethod_t {
+  sel_freefunc free;
+  int nparams;
+  int *param;
+};
+void gmx_selelem_free_method(struct gmx_ana_selmethod_t* method, void* mdata) {
+    sel_freefunc free_func = 0;
+    for (int i = 0; i < method->nparams; ++i)
+        free(&method->param[i]);
+    if (mdata && free_func)
+        free_func(mdata);
+}
+}