Memory bounds checking in asn1 code.

Memory bounds checking in asn1 code.

Check that sprint, strcpy don't overflow.

Avoid some strlen operations when the previous sprintf return value can be used.

Also fix the undefined behaviour `*(long *)x = y` when x isn't a long or character pointer.
ISO/IEC 9899:1999 6.5/7 for the details.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3869)