alpha: Add kcmp and finit_module syscalls

Signed-off-by: Richard Henderson <rth@twiddle.net>
alpha: Eliminate compiler warning from memset macro

Compiling with GCC 4.8 yields several instances of

crypto/vmac.c: In function ‘vmac_final’:
crypto/vmac.c:616:9: warning: value computed is not used [-Wunused-value]
  memset(&mac, 0, sizeof(vmac_t));
         ^
arch/alpha/include/asm/string.h:31:25: note: in definition of macro ‘memset’
     ? __builtin_memset((s),0,(n))          \
                         ^
Converting the macro to an inline function eliminates this problem.

Signed-off-by: Richard Henderson <rth@twiddle.net>
alpha: Modernize lib/mpi/longlong.h

Remove the compile warning for __udiv_qrnnd not having a prototype.
Use the __builtin_alpha_umulh introduced in gcc 4.0.

Signed-off-by: Richard Henderson <rth@twiddle.net>
alpha: Improve atomic_add_unless

Use ll/sc loops instead of C loops around cmpxchg.
Update the atomic64_add_unless block comment to match the code.

Signed-off-by: Richard Henderson <rth@twiddle.net>
alpha: Implement atomic64_dec_if_positive

Signed-off-by: Richard Henderson <rth@twiddle.net>
alpha: Generate dwarf2 unwind info for various kernel entry points.

Having unwind info past the PALcode generated stack frame makes
debugging the kernel significantly easier.

Signed-off-by: Richard Henderson <rth@twiddle.net>
alpha: Fix type compatibility warning for marvel_map_irq

Signed-off-by: Richard Henderson <rth@twiddle.net>