Keep vanetza-idf in obu-firmware, so a plain clone builds the firmware

obu-firmware builds against the vanetza-idf C-ITS library, which until now
came from the colleague's microbu-esp32c5 tree beside the repository and was
not tracked here, so a clone of this repository could not build the firmware
it ships. The library alone is now part of obu-firmware, as
obu-firmware/external/vanetza-idf: their external/vanetza-idf at commit
cf4b99f, unchanged (9775 files; see its PROVENANCE.md). CMake takes it from
there by default; -DVANETZA_IDF_DIR still points the build elsewhere.

The rest of the colleague's tree (their own VAM firmware, PKI tooling,
station-link Python tools, the V2X2MAP bridge) stays out of this repository
and gitignored; nothing is pushed to their repository. NOTES.md, docs/06,
TODO.md and the pcap verifier's usage line point at the new location.

obu-firmware/external/vanetza-idf/vanetza/asn1/support/GeneralizedTime_print.c

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>.
+ * All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#include "asn_internal.h"
+#include "GeneralizedTime.h"
+#include <errno.h>
+
+#ifdef __CYGWIN__
+#include "/usr/include/time.h"
+#else
+#include <time.h>
+#endif  /* __CYGWIN__ */
+
+int
+GeneralizedTime_print(const asn_TYPE_descriptor_t *td, const void *sptr,
+                      int ilevel, asn_app_consume_bytes_f *cb, void *app_key) {
+    const GeneralizedTime_t *st = (const GeneralizedTime_t *)sptr;
+
+    (void)td;  /* Unused argument */
+    (void)ilevel;  /* Unused argument */
+
+    if(st && st->buf) {
+        char buf[32];
+        struct tm tm;
+        int ret;
+
+        errno = EPERM;
+        if(asn_GT2time(st, &tm, 1) == -1 && errno != EPERM)
+            return (cb("<bad-value>", 11, app_key) < 0) ? -1 : 0;
+
+        ret = snprintf(buf, sizeof(buf),
+            "%04d-%02d-%02d %02d:%02d:%02d (GMT)",
+            tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
+            tm.tm_hour, tm.tm_min, tm.tm_sec);
+        assert(ret > 0 && ret < (int)sizeof(buf));
+        return (cb(buf, ret, app_key) < 0) ? -1 : 0;
+    } else {
+        return (cb("<absent>", 8, app_key) < 0) ? -1 : 0;
+    }
+}