Mark SRP_VBASE_get_by_user() as deprecated

The function SRP_VBASE_get_by_user() is declared as deprecated but the
implementation was not.
Reviewed-by: NRich Salz <rsalz@openssl.org>

crypto/srp/srp_vfy.c

@@ -502,6 +502,7 @@ static SRP_user_pwd *find_user(SRP_VBASE *vb, char *username)
     return NULL;
 }
 
+ #if OPENSSL_API_COMPAT < 0x10100000L
 /*
  * DEPRECATED: use SRP_VBASE_get1_by_user instead.
  * This method ignores the configured seed and fails for an unknown user.
@@ -512,6 +513,7 @@ SRP_user_pwd *SRP_VBASE_get_by_user(SRP_VBASE *vb, char *username)
 {
     return find_user(vb, username);
 }
+#endif
 
 /*
  * Ownership of the returned pointer is released to the caller.