buffers: add compile-time option to set buffer alignment

Type: improvement
Change-Id: I88c4c45bed0bdd8686e17e4f77a7d32a08c995aa
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vlib/buffer.h b/src/vlib/buffer.h
index a747ea9..7d45689 100644
--- a/src/vlib/buffer.h
+++ b/src/vlib/buffer.h
@@ -47,8 +47,7 @@
 #include <vppinfra/lock.h>
 #include <vlib/error.h>		/* for vlib_error_t */
 
-#include <vlib/config.h>	/* for __PRE_DATA_SIZE */
-#define VLIB_BUFFER_PRE_DATA_SIZE	__PRE_DATA_SIZE
+#include <vlib/config.h> /* for VLIB_BUFFER_PRE_DATA_SIZE */
 
 #define VLIB_BUFFER_DEFAULT_DATA_SIZE (2048)