Fix bug introduced in dbf69cf

(Was writing outside array bounds.)
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 1beefab..38b4029 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -134,7 +134,7 @@
                                                 size_t *olen )
 {
     unsigned char *p = buf;
-    unsigned char sig_alg_list[20];
+    unsigned char *sig_alg_list = buf + 6;
     size_t sig_alg_len = 0;
 
     *olen = 0;
@@ -218,8 +218,6 @@
     *p++ = (unsigned char)( ( sig_alg_len >> 8 ) & 0xFF );
     *p++ = (unsigned char)( ( sig_alg_len      ) & 0xFF );
 
-    memcpy( p, sig_alg_list, sig_alg_len );
-
     *olen = 6 + sig_alg_len;
 }