ip_header.h confuses bit order with byte order

[Jiri Svoboda]

ip_header.h incorrectly uses the ARCH_IS_BIG_ENDIAN macro to detect whether C bitfields are stored in high-to-low or low-to-high order. This is incorrect, because bitfield order has nothing to do with byte order (ARCH_IS_BIG_ENDIAN tells us byte order is big-endian).

Either we need to supply macros for checking bitfield order, or, preferably, avoid bit fields like in the rest of the code.

[Jakub Jermář]

Fixed in mainline,997.