incorporate header fixes proposed in bug 3097

Not sure these are *really* needed, but I suppose they don't hurt

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/include/libbb.h b/include/libbb.h
index 6358e65..dd82e97 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -33,6 +33,9 @@
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/types.h>
+#ifndef major
+# include <sys/sysmacros.h>
+#endif
 #include <sys/wait.h>
 #include <termios.h>
 #include <time.h>