Record trap_arg{0,1,2} for the linux-user signal frame.
Fill in the stores to trap_arg{1,2} that were missing
from the previous user-only alpha_cpu_tlb_fill function.
Use maperr to simplify computation of trap_arg1.
Remove the code for EXCP_MMFAULT from cpu_loop, as
that part is now handled by cpu_loop_exit_sigsegv.
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>