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FLASHING.md says how to take a newer version of the colleague's tree (copy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/NULL.c

@@ -0,0 +1,131 @@
+/*-
+ * Copyright (c) 2003, 2005 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#include "asn_internal.h"
+#include "NULL.h"
+
+/*
+ * NULL basic type description.
+ */
+static const ber_tlv_tag_t asn_DEF_NULL_tags[] = {
+    (ASN_TAG_CLASS_UNIVERSAL | (5 << 2))
+};
+asn_TYPE_operation_t asn_OP_NULL = {
+    NULL_free,
+#if !defined(ASN_DISABLE_PRINT_SUPPORT)
+    NULL_print,
+#else
+    0,
+#endif  /* !defined(ASN_DISABLE_PRINT_SUPPORT) */
+    NULL_compare,
+    NULL_copy,
+#if !defined(ASN_DISABLE_BER_SUPPORT)
+    NULL_decode_ber,
+    NULL_encode_der,  /* Special handling of DER encoding */
+#else
+    0,
+    0,
+#endif  /* !defined(ASN_DISABLE_BER_SUPPORT) */
+#if !defined(ASN_DISABLE_XER_SUPPORT)
+    NULL_decode_xer,
+    NULL_encode_xer,
+#else
+    0,
+    0,
+#endif  /* !defined(ASN_DISABLE_XER_SUPPORT) */
+#if !defined(ASN_DISABLE_JER_SUPPORT)
+    NULL_decode_jer,
+    NULL_encode_jer,
+#else
+    0,
+    0,
+#endif  /* !defined(ASN_DISABLE_JER_SUPPORT) */
+#if !defined(ASN_DISABLE_OER_SUPPORT)
+    NULL_decode_oer,
+    NULL_encode_oer,
+#else
+    0,
+    0,
+#endif  /* !defined(ASN_DISABLE_OER_SUPPORT) */
+#if !defined(ASN_DISABLE_UPER_SUPPORT)
+    NULL_decode_uper,  /* Unaligned PER decoder */
+    NULL_encode_uper,  /* Unaligned PER encoder */
+#else
+    0,
+    0,
+#endif  /* !defined(ASN_DISABLE_UPER_SUPPORT) */
+#if !defined(ASN_DISABLE_APER_SUPPORT)
+    NULL_decode_aper,  /* Aligned PER decoder */
+    NULL_encode_aper,  /* Aligned PER encoder */
+#else
+    0,
+    0,
+#endif  /* !defined(ASN_DISABLE_APER_SUPPORT) */
+#if !defined(ASN_DISABLE_RFILL_SUPPORT)
+    NULL_random_fill,
+#else
+    0,
+#endif  /* !defined(ASN_DISABLE_RFILL_SUPPORT) */
+    0  /* Use generic outmost tag fetcher */
+};
+asn_TYPE_descriptor_t asn_DEF_NULL = {
+    "NULL",
+    "NULL",
+    &asn_OP_NULL,
+    asn_DEF_NULL_tags,
+    sizeof(asn_DEF_NULL_tags) / sizeof(asn_DEF_NULL_tags[0]),
+    asn_DEF_NULL_tags,  /* Same as above */
+    sizeof(asn_DEF_NULL_tags) / sizeof(asn_DEF_NULL_tags[0]),
+    {
+#if !defined(ASN_DISABLE_OER_SUPPORT)
+        0,
+#endif  /* !defined(ASN_DISABLE_OER_SUPPORT) */
+#if !defined(ASN_DISABLE_UPER_SUPPORT) || !defined(ASN_DISABLE_APER_SUPPORT)
+        0,
+#endif  /* !defined(ASN_DISABLE_UPER_SUPPORT) || !defined(ASN_DISABLE_APER_SUPPORT) */
+#if !defined(ASN_DISABLE_JER_SUPPORT)
+        0,
+#endif  /* !defined(ASN_DISABLE_JER_SUPPORT) */
+        asn_generic_no_constraint
+    },
+    0, 0,  /* No members */
+    0  /* No specifics */
+};
+
+void
+NULL_free(const asn_TYPE_descriptor_t *td, void *ptr,
+          enum asn_struct_free_method method) {
+    if(td && ptr) {
+        switch(method) {
+        case ASFM_FREE_EVERYTHING:
+            FREEMEM(ptr);
+            break;
+        case ASFM_FREE_UNDERLYING:
+            break;
+        case ASFM_FREE_UNDERLYING_AND_RESET:
+            memset(ptr, 0, sizeof(NULL_t));
+            break;
+        }
+    }
+}
+
+int
+NULL_compare(const asn_TYPE_descriptor_t *td, const void *a, const void *b) {
+    (void)td;
+    (void)a;
+    (void)b;
+    return 0;
+}
+
+int
+NULL_copy(const asn_TYPE_descriptor_t *td, void **a, const void *b) {
+    (void)td;
+
+    if(b && !*a) {
+        *a = CALLOC(1, sizeof(NULL_t));
+        if (!*a) return -1;
+    }
+
+    return 0;
+}