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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#ifndef	OER_DECODER_H
+#define	OER_DECODER_H
+
+#include "asn_application.h"
+#include "oer_support.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct asn_TYPE_descriptor_s;	/* Forward declaration */
+struct asn_codec_ctx_s;		/* Forward declaration */
+
+/*
+ * The Octet Encoding Rules (OER, X.696 08/2015) decoder for any given type.
+ * This function may be invoked directly by the application.
+ * Parses CANONICAL-OER and BASIC-OER.
+ */
+asn_dec_rval_t oer_decode(const struct asn_codec_ctx_s *opt_codec_ctx,
+	const struct asn_TYPE_descriptor_s *type_descriptor,
+	void **struct_ptr,	/* Pointer to a target structure's pointer */
+	const void *buffer,	/* Data to be decoded */
+	size_t size		/* Size of that buffer */
+	);
+
+/*
+ * Type of generic function which decodes the byte stream into the structure.
+ */
+typedef asn_dec_rval_t(oer_type_decoder_f)(
+    const struct asn_codec_ctx_s *opt_codec_ctx,
+    const struct asn_TYPE_descriptor_s *type_descriptor,
+    const asn_oer_constraints_t *constraints,
+    void **struct_ptr,
+    const void *buf_ptr,
+    size_t size);
+
+/*
+ * Swallow the Open Type (X.696 (08/2015), #30) into /dev/null.
+ * RETURN VALUES:
+ *      -1:     Fatal error deciphering length.
+ *       0:     More data expected than bufptr contains.
+ *      >0:     Number of bytes used from bufptr.
+ */
+ssize_t oer_open_type_skip(const void *bufptr, size_t size);
+
+/*
+ * Read the Open Type (X.696 (08/2015), #30).
+ * RETURN VALUES:
+ *       0:     More data expected than bufptr contains.
+ *      -1:     Fatal error deciphering length.
+ *      >0:     Number of bytes used from bufptr.
+ */
+ssize_t oer_open_type_get(const asn_codec_ctx_t *opt_codec_ctx,
+                          const struct asn_TYPE_descriptor_s *td,
+                          const asn_oer_constraints_t *constraints,
+                          void **struct_ptr, const void *bufptr, size_t size);
+
+/*
+ * Length-prefixed buffer decoding for primitive types.
+ */
+oer_type_decoder_f oer_decode_primitive;
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* OER_DECODER_H */