Fix include guard in tree.h and ngx-queue.h

The C99 standard reserves all identifiers (including macros) that start with an
underscore and a capital letter.

Fixes #260.

include/uv-private/ngx-queue.h

@@ -4,8 +4,8 @@
  */
 
 
-#ifndef _NGX_QUEUE_H_INCLUDED_
-#define _NGX_QUEUE_H_INCLUDED_
+#ifndef NGX_QUEUE_H_INCLUDED_
+#define NGX_QUEUE_H_INCLUDED_
 
 
 typedef struct ngx_queue_s  ngx_queue_t;
@@ -103,4 +103,4 @@ struct ngx_queue_s {
     for ((q) = ngx_queue_head(h); (q) != (h); (q) = ngx_queue_next(q))
 
 
-#endif /* _NGX_QUEUE_H_INCLUDED_ */
+#endif /* NGX_QUEUE_H_INCLUDED_ */

include/uv-private/tree.h

@@ -23,8 +23,8 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef  _UV_TREE_H_
-#define  _UV_TREE_H_
+#ifndef  UV_TREE_H_
+#define  UV_TREE_H_
 
 #define __unused
 
@@ -759,4 +759,4 @@ name##_RB_MINMAX(struct name *head, int val)                                  \
       ((x) != NULL) && ((y) = name##_RB_PREV(x), (x) != NULL);                \
        (x) = (y))
 
-#endif  /* _UV_TREE_H_ */
+#endif  /* UV_TREE_H_ */