Conditional sys/sysmacros.h inclusion

[Ingo Feinerer <feinerer@xxxxxxxx>]

Commit 380fe7d4548a99bfcfc1594b6f0b3dd2369978f1 broke the functionality on
OpenBSD as it has no sys/sysmacros.h. So replicate commit
08572e7db2120bc45db732d02409dfd3346b8e51 but use explicit OS checks instead of
AC_HEADER_MAJOR.

Signed-off-by: Ingo Feinerer <feinerer@xxxxxxxx>

diff --git a/lib/libv4lconvert/control/libv4lcontrol.c b/lib/libv4lconvert/control/libv4lcontrol.c
index 59f28b137b..793e19f299 100644
--- a/lib/libv4lconvert/control/libv4lcontrol.c
+++ b/lib/libv4lconvert/control/libv4lcontrol.c
@@ -20,7 +20,9 @@
  */
 
 #include <sys/types.h>
+#ifndef __OpenBSD__
 #include <sys/sysmacros.h>
+#endif
 #include <sys/mman.h>
 #include <fcntl.h>
 #include <sys/stat.h>