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FLASHING.md says how to take a newer version of the colleague's tree (copy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

@@ -0,0 +1,87 @@
+/*-
+ * Copyright (c) 2004-2017 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#ifndef	_JER_ENCODER_H_
+#define	_JER_ENCODER_H_
+
+#include "asn_application.h"
+#include "jer_support.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct asn_TYPE_descriptor_s;	/* Forward declaration */
+
+/*
+ * Flags used by the jer_encode() and (*jer_type_encoder_f), defined below
+ */
+enum jer_encoder_flags_e {
+	/* Mode of encoding */
+	JER_F	        = 0x01,	/* JER (pretty-printing) */
+	JER_F_MINIFIED	= 0x02,	/* JER (minified) */
+};
+
+/*
+ * The JER encoder of any type. May be invoked by the application.
+ * Produces JER output.
+ */
+asn_enc_rval_t jer_encode(const struct asn_TYPE_descriptor_s *type_descriptor,
+                          const void *struct_ptr, /* Structure to be encoded */
+                          enum jer_encoder_flags_e jer_flags,
+                          asn_app_consume_bytes_f *consume_bytes_cb,
+                          void *app_key /* Arbitrary callback argument */
+);
+
+/*
+ * The variant of the above function which dumps the JER
+ * output into the chosen file pointer.
+ * RETURN VALUES:
+ * 	 0: The structure is printed.
+ * 	-1: Problem printing the structure.
+ * WARNING: No sensible errno value is returned.
+ */
+int jer_fprint(FILE *stream, const struct asn_TYPE_descriptor_s *td,
+               const void *struct_ptr);
+
+/*
+ * A helper function that uses JER encoding/decoding to verify that:
+ * - Both structures encode into the same JER.
+ * - Both resulting JER byte streams can be decoded back.
+ * - Both decoded structures encode into the same JER (round-trip).
+ * All of this verifies equivalence between structures and a round-trip.
+ * ARGUMENTS:
+ *  (opt_debug_stream)  - If specified, prints ongoing details.
+ */
+enum jer_equivalence_e {
+    JEQ_SUCCESS,          /* The only completely positive return value */
+    JEQ_FAILURE,          /* General failure */
+    JEQ_ENCODE1_FAILED,   /* First structure JER encoding failed */
+    JEQ_ENCODE2_FAILED,   /* Second structure JER encoding failed */
+    JEQ_DIFFERENT,        /* Structures encoded into different JER */
+    JEQ_DECODE_FAILED,    /* Decode of the JER data failed */
+    JEQ_ROUND_TRIP_FAILED /* Bad round-trip */
+};
+enum jer_equivalence_e jer_equivalent(
+    const struct asn_TYPE_descriptor_s *type_descriptor, const void *struct1,
+    const void *struct2, FILE *opt_debug_stream);
+
+/*
+ * Type of the generic JER encoder.
+ */
+typedef asn_enc_rval_t(jer_type_encoder_f)(
+    const struct asn_TYPE_descriptor_s *type_descriptor,
+    const asn_jer_constraints_t *constraints,
+    const void *struct_ptr, /* Structure to be encoded */
+    int ilevel,             /* Level of indentation */
+    enum jer_encoder_flags_e jer_flags,
+    asn_app_consume_bytes_f *consume_bytes_cb, /* Callback */
+    void *app_key                              /* Arbitrary callback argument */
+);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* _JER_ENCODER_H_ */