Fix AIX build when no-shared is passed to Configure.

Fix AIX build when no-shared is passed to Configure.

AIX shared libs are also .a files so the AIX platform staticname()
appends a '_a' to the name to avoid a collision.  However, this
must not be done when no-shared is passed to Configure or the
binaries that link with -lcrypto and -lssl be unable to link as
those libraries won't exist without the '_a' suffix.

CLA: trivial

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18006)