Fix sigreturn decoding on MIPS

The "return 0" line was accidentally deleted circa 2007,
which made sigreturn on MIPS always display "= 0" return
instead of more informative " = ? (mask now [MASK])".

* strace.c (sys_sigreturn): Add wrongly deleted "return 0" line

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
1 file changed