fix stacked vmlinux struct parsing issue

tests/failing_tests/vmlinux/requests2.py

@@ -0,0 +1,19 @@
+from vmlinux import struct_kobj_type
+from pythonbpf import bpf, section, bpfglobal, compile_to_ir
+import logging
+from ctypes import c_void_p
+
+
+@bpf
+@section("kprobe/blk_mq_start_request")
+def example(ctx: c_void_p):
+    print(f"data lengt")
+
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+
+compile_to_ir("requests.py", "requests.ll", loglevel=logging.INFO)