Add CERT_PREFIX to libbitcoin-network test flags.

Author: pmienk

generate4.xml

@@ -403,6 +403,7 @@
         <sources path="src" />
       </product>
       <product prefix="bin" path="test" target_name="libbitcoin-network-test" test="true" option="tests" uuid="d28fc18a-8b81-4247-92ee-6967feefeeff" >
+        <flag value="DCERT_PREFIX=&quot;\&quot;${src_dir}/test/ssl/wolfssl/wolfcrypt/test/\&quot;&quot;" />
         <runner>
           <!--<run test="empty_tests" />-->
           <!--<run test="p2p_tests" />-->