bsd: fix horrible m_* macro clash

bsd defines some m_ macros, for example m_flags, to save some typing.  However
if you have a variable of the same name in another header, for example
m_flags, have fun trying to compile your code.

Expand the code in place and eliminate the macros.

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>