Configurations/10-main.conf: reinstate soname on Solaris.

The flag was apparently omitted in switch from Makefile.shared to
shared-info.pl. Do put it back! And in the process move all
solaris-shared flags from shared-info.pl to solaris-common.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6446)