Remove V_ASN1_APP_CHOOSE.

V_ASN1_APP_CHOOSE has been discouraged by OpenSSL since 2000:
https://git.openssl.org/gitweb/?p=openssl.git;a=blob;f=CHANGES;h=824f421b8d331ba2a2009dbda333a57493bedb1e;hb=fb047ebc87b18bdc4cf9ddee9ee1f5ed93e56aff#l10848

Instead, upstream recommends an MBSTRING_* constant.
https://www.openssl.org/docs/man1.1.1/man3/X509_NAME_add_entry_by_NID.html

This function is a bit overloaded:

MBSTRING_* means "Decode my input from this format and then re-encode it
using whatever string type best suits the NID (usually UTF8String, but
some NIDs require PrintableString)".

V_ASN1_APP_CHOOSE means "This is a Latin-1 string. Without looking at
the NID, pick one of PrintableString, IA5String, or T61String".

The latter is almost certainly not what callers want. If they want a
particular type, they can always force it by passing a particular
V_ASN1_* constant. This removes the only use of ASN1_PRINTABLE_type
within the library, though there is one external use still.

Update-Note: V_ASN1_APP_CHOOSE is removed. I only found one use, which
has been fixed.

Change-Id: Id36376dd0ec68559bbbb366e2305d42be5ddac67
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/49067
Reviewed-by: Adam Langley <agl@google.com>

crypto/x509/x509name.c

diff --git a/crypto/x509/x509name.c b/crypto/x509/x509name.c
index 0bf3459..23e7553 100644
--- a/crypto/x509/x509name.c
+++ b/crypto/x509/x509name.c
@@ -367,10 +367,7 @@
     if (!i)
         return (0);
     if (type != V_ASN1_UNDEF) {
-        if (type == V_ASN1_APP_CHOOSE)
-            ne->value->type = ASN1_PRINTABLE_type(bytes, len);
-        else
-            ne->value->type = type;
+        ne->value->type = type;
     }
     return (1);
 }

include/openssl/asn1.h

diff --git a/include/openssl/asn1.h b/include/openssl/asn1.h
index 497ad7c..4f6fb3b 100644
--- a/include/openssl/asn1.h
+++ b/include/openssl/asn1.h
@@ -111,10 +111,6 @@
 // V_ASN1_UNDEF is used in some APIs to indicate an ASN.1 element is omitted.
 #define V_ASN1_UNDEF (-1)
 
-// V_ASN1_APP_CHOOSE is used in some APIs to specify a default ASN.1 type based
-// on the context.
-#define V_ASN1_APP_CHOOSE (-2)
-
 // V_ASN1_OTHER is used in |ASN1_TYPE| to indicate a non-universal ASN.1 type.
 #define V_ASN1_OTHER (-3)