Allow SHA-1 in SSL renegotiation tests

In the TLS test client, allow SHA-1 as a signature hash algorithm.
Without this, the renegotation tests failed.

A previous commit had allowed SHA-1 via the certificate profile but
that only applied before the initial negotiation which includes the
signature_algorithms extension.
diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index bdaae31..c8eb145 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -395,6 +395,22 @@
 
     return( 0 );
 }
+
+static int ssl_sig_hashes_for_test[] = {
+#if defined(MBEDTLS_SHA512_C)
+    MBEDTLS_MD_SHA512,
+    MBEDTLS_MD_SHA384,
+#endif
+#if defined(MBEDTLS_SHA256_C)
+    MBEDTLS_MD_SHA256,
+    MBEDTLS_MD_SHA224,
+#endif
+#if defined(MBEDTLS_SHA1_C)
+    /* Allow SHA-1 as we use it extensively in tests. */
+    MBEDTLS_MD_SHA1,
+#endif
+    MBEDTLS_MD_NONE
+};
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
 int main( int argc, char *argv[] )
@@ -1096,6 +1112,7 @@
        rely on it heavily. */
     crt_profile_for_test.allowed_mds |= MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA1 );
     mbedtls_ssl_conf_cert_profile( &conf, &crt_profile_for_test );
+    mbedtls_ssl_conf_sig_hashes( &conf, ssl_sig_hashes_for_test );
 
     if( opt.debug_level > 0 )
         mbedtls_ssl_conf_verify( &conf, my_verify, NULL );