Add region interprocedural fixpoint error test

tests/regression/09-regions/40-zstd-thread-pool-region.c

@@ -0,0 +1,34 @@
+// SKIP PARAM: --set ana.activated[+] region
+// FIXPOINT
+#include<stdlib.h>
+#include<pthread.h>
+#include<goblint.h>
+
+typedef struct POOL_job_s {
+    void *opaque;
+} POOL_job;
+
+typedef struct POOL_ctx_s {
+    POOL_job *queue;
+} POOL_ctx;
+
+POOL_ctx* ctx_global;
+
+POOL_ctx* POOL_create(size_t numThreads, size_t queueSize)
+{
+    POOL_ctx* ctx_create;
+    ctx_create = (POOL_ctx*)malloc(sizeof(POOL_ctx));
+    ctx_create->queue = (POOL_job*)malloc(queueSize * sizeof(POOL_job));
+
+    int r; // rand
+    if (r)
+        ctx_global = ctx_create; // pretend escape
+    return ctx_create;
+}
+
+int main() {
+    while (1) {
+        POOL_ctx *ctx_main;
+        ctx_main = POOL_create(20, 10);
+    }
+}