ring: prepare setup_rx_ring_layout for support in v2/v3

Prepare setup_rx_ring_layout for both, v2 and v3. Also do some checks
during compile time if offsets stay the same as we operate on different
union mappings.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/built_in.h b/built_in.h
index fa2f0c8..ea81257 100644
--- a/built_in.h
+++ b/built_in.h
@@ -153,6 +153,10 @@ typedef uint8_t		u8;
 # define build_bug_on_zero(e)	(sizeof(char[1 - 2 * !!(e)]) - 1)
 #endif
 
+#ifndef build_bug_on
+# define build_bug_on(e)	((void)sizeof(char[1 - 2*!!(e)]))
+#endif
+
 #ifndef bug_on
 # define bug_on(cond)		assert(!(cond))
 #endif