Move call to ssl_consume_current_message()

Subsequent commits will potentially inject buffered
messages after the last incoming message has been
consumed, but before a new one is fetched. As a
preparatory step to this, this commit moves the call
to ssl_consume_current_message() from ssl_read_record_layer()
to the calling function mbedtls_ssl_read_record().
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 23a5bdd..54bb443 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4299,6 +4299,10 @@
     {
         do {
 
+            ret = ssl_consume_current_message( ssl );
+            if( ret != 0 )
+                return( ret );
+
             ret = ssl_read_record_layer( ssl );
             if( ret == MBEDTLS_ERR_SSL_CONTINUE_PROCESSING )
                 continue;
@@ -4429,22 +4433,7 @@
     int ret;
 
     /*
-     * Step A
-     *
-     * Consume last content-layer message and potentially
-     * update in_msglen which keeps track of the contents'
-     * consumption state.
-     */
-
-    ret = ssl_consume_current_message( ssl );
-    if( ret != 0 )
-        return( ret );
-
-    /*
-     * Step B
-     *
      * Fetch and decode new record if current one is fully consumed.
-     *
      */
 
     if( ssl->in_msglen > 0 )