Squatting these names is rather rude. Also hex_to_string and
string_to_hex do the opposite of what one would expect, so rename them
to something a bit less confusing.

Update-Note: This removes some random utility functions. name_cmp is
very specific to OpenSSL's config file format, so it's unlikely anyone
is relying on it. I removed the one use of hex_to_string and
string_to_hex I could find.

Change-Id: I01554885ad306251e6982100d0b15cd89b1cdea7
Reviewed-on: https://boringssl-review.googlesource.com/c/33364
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>