#24 Add syscall entries for mips64 (n32 and n64)

[Joel Martin]

I sent this to the list but I think it's too big and
the moderator hasn't gotten around to letting it
through. So attached is a patch to add system call
entries for Linux MIPS n32 and n64 ABIs.

Also fixes a compile issue for n32/n64 although, I'm
not sure the signal.c change is exactly correct. These
changes do allow me to build an strace as n64 which can
trace o32, n32 and n64 programs using the same strace
executable.

[Joel Martin]

mips64 (n32/n64) syscall entries

[Eugene Syromyatnikov]

Fixed in commit 542c2c6fe2b93ae73221dd5c5c8ed95a73b676e4.