linux-user/alpha: Fix target rlimits for alpha and rearrange for clarity

linux-user/alpha: Fix target rlimits for alpha and rearrange for clarity

Alpha uses different values of some TARGET_RLIMIT_* constants, which were
missing and caused bugs like #577, fixed thus.  Also rearranged all three
(alpha, mips and sparc) that differ from everyone else for clarity.

Signed-off-by: Serge Belyshev <belyshev@depni.sinp.msu.ru>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/577
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <87y236lpwb.fsf@depni.sinp.msu.ru>
[lv: replace tabs by spaces]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>