Simplify
update gcc 4.8 support for 4.8.1 -> 4.8.2.
 Modify some macros and add some new macros for CPU family and model
to reduce code duplication and to avoid bug.

CPUID_TO_STEPPING(cpuid)	(not changed)

CPUID_TO_FAMILY(cpuid)		(new)
CPUID_TO_MODEL(cpuid)		(new)

	Return the display family and the display model.
	The macro names are the same as FreeBSD.

CPUID_TO_BASEFAMILY(cpuid)	(The old name was CPUID2FAMILY)
CPUID_TO_BASEMODEL(cpuid)	(The old name was CPUID2MODEL)

	Only for the base field.

CPUID_TO_EXTFAMILY(cpuid)	(The old name was CPUID2EXTFAMILY)
CPUID_TO_EXTMODEL(cpuid)	(The old name was CPUID2EXTMODEL)

	Only for the extended field.

See http://mail-index.netbsd.org/port-amd64/2013/11/12/msg001978.html
Describe the differences between file system internal and external snapshots.
Check stack alignment on hppa.
Fix the bpfjit build.

add one more __unused attribute to shut gcc4.8 off.

fix unused variable warning
remove trigger happy assertion. in m_adj negative lengths are valid.
Add stack alignement checking for sparc64
bpf_deliver: convert to bpf_filter_ext().
NPF: convert to bpf_jit_generate()/bpf_jit_freecode().
Add rumpkern_sljit and rumpnet_bpfjit modules.
Build rumpkern_sljit and rumpnet_bpfjit; include them into the sets.
Enable bpfjit for npftest.
sljit is only available on very few architectures, so do not try to build
it on all.
We do not want to build the code model markes when creating the 32bit
compat libs for sparc64
make sure that .text.startup and .text.unlikely end up in the
text section.  GCC 4.8 ofppc kernels now boot, though they are
unable to load the symbol table correctly.

also tested with GCC 4.5 and ofppc (pegasosII.)
move variable use and initialisation inside the #ifdef / block that uses it.
Build and install sljit and bpfjit rump components iff ${MKSLJIT} != "no".