Track vex r2910 (infrastructural improvements in representation of
endianness in VEX).

In short: in m_machine.c, VG_(machine_get_hwcaps), get the endianness
of the host, and pass it through to all places (in VEX) where it is
required.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14184 a5019735-40e9-0310-863c-91ae7b9d1cf9
Factor out VG_(exit_now) to contain the syscall incantation to terminate
the process. Make ML_(am_exit) and VG_(exit) use it, thereby avoiding 
double maintenance.
Introduce libcbase_assert macro and use it in VG_(strncpy_safely) to 
document the case that function cannot handle.
Add stub functions to memcheck/tests/unit_libcbase.c to satisfy new
dependencies.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14185 a5019735-40e9-0310-863c-91ae7b9d1cf9
Change VG_(strncpy_safely) to use VG_(strncpy) to get the same padding
behaviour. 


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14186 a5019735-40e9-0310-863c-91ae7b9d1cf9
Update a comment so it won't need updating in the future.
No functional change.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14187 a5019735-40e9-0310-863c-91ae7b9d1cf9