Keep the colleague's microbu-esp32c5 tree in this repository

obu-firmware builds against vanetza-idf from microbu-esp32c5/external, but
that tree was gitignored, so a clone of this repository could not build the
firmware it ships. It is now committed here as ordinary files in its own
folder, microbu-esp32c5/: the colleague's commit cf4b99f plus the V2X2MAP
bridge's signature verification (--trust) used on the bench. Nothing is
fetched from or pushed to the colleague's repository; this repository and
its remotes carry everything. The folder's own .gitignore keeps build output,
downloaded components and private key material out, as it did there; the
committed file set is identical to that repository's tracked files.

The ESP32-C5 is still flashed from obu-firmware/, which only takes
vanetza-idf from microbu-esp32c5/, so the two stay separate folders.
FLASHING.md says how to take a newer version of the colleague's tree (copy
it over the folder, rebuild, test, commit).

microbu-esp32c5/external/vanetza-idf/vanetza/asn1/support/asn_ioc.h

@@ -0,0 +1,51 @@
+/*
+ * Run-time support for Information Object Classes.
+ * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#ifndef	ASN_IOC_H
+#define	ASN_IOC_H
+
+#include "asn_system.h"		/* Platform-specific types */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct asn_TYPE_descriptor_s;
+struct asn_ioc_cell_s;
+
+/*
+ * X.681, #13
+ */
+typedef struct asn_ioc_set_s {
+    size_t rows_count;
+    size_t columns_count;
+    const struct asn_ioc_cell_s *rows;
+} asn_ioc_set_t;
+
+
+typedef struct asn_ioc_cell_s {
+    const char *field_name; /* Is equal to corresponding column_name */
+    enum {
+        aioc__undefined = 0,
+        aioc__value,
+        aioc__type,
+        aioc__open_type,
+    } cell_kind;
+    struct asn_TYPE_descriptor_s *type_descriptor;
+    const void *value_sptr;
+    struct {
+        size_t types_count;
+        struct {
+            unsigned choice_position;
+        } *types;
+    } open_type;
+} asn_ioc_cell_t;
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* ASN_IOC_H */