util/*.num: deassign ordinal numbers from new symbols

util/*.num: deassign ordinal numbers from new symbols

Symbols that have appeared since 1.1.1 was released are considered
unassigned in the development branch.   This is marked by having a
question mark as its ordinal number.

This introduces two new markers to be used instead of ordinal numbers:

    ?   signifying it gets the previous symbol's number plus one
    ?+  signifying it gets the same number as the previous symbol

'?+' should remain rare, but is useful to create aliases when needed
(for example when two different symbols clash because they only differ
in character case, see include/openssl/symhacks.h)

The intention is that a development branch won't have set numbers for
new symbols, and that the final numbers will only get allocated when
making beta or final releases.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10348)