Make some test data of unknown ASN.1 types slightly less invalid

EXTERNAL, EMBEDDED PDV, and CHARACTER STRING are actually constructed!
They're encoded as some implicitly-tagged SEQUENCE. I couldn't be
bothered to fill in valid contents thought.

While I'm here, make RELATIVE-OID non-empty. That is the most likely new
type for us to pay attention to here, just because we borrowed them for
trust anchor IDs. (I'm not totally clear on whether the empty relative
OID is a valid relative OID. Meh.)

Change-Id: I193e5fb800d317cad8711a09078ac15adf80d76a
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/81728
Auto-Submit: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

crypto/x509/x509_test.cc

diff --git a/crypto/x509/x509_test.cc b/crypto/x509/x509_test.cc
index e17f2b2..c3abf35 100644
--- a/crypto/x509/x509_test.cc
+++ b/crypto/x509/x509_test.cc
@@ -7223,14 +7223,17 @@
       // These types are not actually supported by the library, but we accept
       // them as |V_ASN1_OTHER|.
       {7 /* ObjectDescriptor */, "", V_ASN1_OTHER, std::string("\x07\x00", 2)},
-      {8 /* EXTERNAL */, "", V_ASN1_OTHER, std::string("\x08\x00", 2)},
+      {CBS_ASN1_CONSTRUCTED | 8 /* EXTERNAL */, "", V_ASN1_OTHER,
+       std::string("\x28\x00", 2)},
       {9 /* REAL */, "", V_ASN1_OTHER, std::string("\x09\x00", 2)},
-      {11 /* EMBEDDED PDV */, "", V_ASN1_OTHER, std::string("\x0b\x00", 2)},
-      {13 /* RELATIVE-OID */, "", V_ASN1_OTHER, std::string("\x0d\x00", 2)},
+      {CBS_ASN1_CONSTRUCTED | 11 /* EMBEDDED PDV */, "", V_ASN1_OTHER,
+       std::string("\x2b\x00", 2)},
+      {13 /* RELATIVE-OID */, "\x01", V_ASN1_OTHER, "\x0d\x01\x01"},
       {14 /* TIME */, "", V_ASN1_OTHER, std::string("\x0e\x00", 2)},
       {15 /* not a type; reserved value */, "", V_ASN1_OTHER,
        std::string("\x0f\x00", 2)},
-      {29 /* CHARACTER STRING */, "", V_ASN1_OTHER, std::string("\x1d\x00", 2)},
+      {CBS_ASN1_CONSTRUCTED | 29 /* CHARACTER STRING */, "", V_ASN1_OTHER,
+       std::string("\x3d\x00", 2)},
 
       // Non-universal tags are allowed as |V_ASN1_OTHER| too.
       {CBS_ASN1_APPLICATION | CBS_ASN1_CONSTRUCTED | 42, "", V_ASN1_OTHER,