ARM: fix sigreturn decoding
ARM: fix sigreturn decoding

Decoding of test/sigreturn testcase:
Was:
sigreturn() (mask [QUIT TRAP ABRT BUS SEGV USR2 PIPE STKFLT STOP XCPU VTALRM PROF WINCH IO PWR RTMIN]) = 0
Now:
sigreturn() (mask [CHLD RT_1 RT_3 RT_31 RT_32]) = 0

Signed-off-by: Denys Vlasenko <50fbbd36fe0f9c8261d4a3c762c8c29ffb35e48f@redhat.com>

vrastogi/strace,YUPlayGodDev/platform_external_strace,Yu-AndroidM/android_external_strace,Distrotech/strace,bigzz/strace_android,geekboxzone/mmallow_external_strace,YUPlayGodDev/platform_external_strace,DirtyUnicorns/android_external_strace,Infinitive-OS/platform_external_strace,pombredanne/strace,xin3liang/platform_external_strace,MonkeyZZZZ/platform_external_strace,geekboxzone/lollipop_external_strace,AOSP-YU/platform_external_strace,Yu-AndroidM/android_external_strace,YUPlayGodDev/platform_external_strace,cuviper/strace,Distrotech/strace,MonkeyZZZZ/platform_external_strace,geekboxzone/lollipop_external_strace,geofft/strace,cuviper/strace,Yu-AndroidM/android_external_strace,YUPlayGodDev/platform_external_strace,geekboxzone/mmallow_external_strace,Infinitive-OS/platform_external_strace,vrastogi/strace,Infinitive-OS/platform_external_strace,DirtyUnicorns/android_external_strace,geofft/strace,pombredanne/strace,Saruta/strace,android-ia/platform_external_strace,pombredanne/strace,cuviper/strace,cuviper/strace,AOSP-YU/platform_external_strace,lkundrak/strace,MonkeyZZZZ/platform_external_strace,lkundrak/strace,geofft/strace,geekboxzone/lollipop_external_strace,android-ia/platform_external_strace,vrastogi/strace,vrastogi/strace,YUPlayGodDev/platform_external_strace,Saruta/strace,MonkeyZZZZ/platform_external_strace,DirtyUnicorns/android_external_strace,pombredanne/strace,DirtyUnicorns/android_external_strace,Distrotech/strace,xin3liang/platform_external_strace,lkundrak/strace,kapdop/android_external_strace,AOSP-YU/platform_external_strace,bigzz/strace_android,DirtyUnicorns/android_external_strace,Infinitive-OS/platform_external_strace,TeamExodus/external_strace,Saruta/strace,lkundrak/strace,CyanogenMod/android_external_strace,kapdop/android_external_strace,AOSP-YU/platform_external_strace,CyanogenMod/android_external_strace,TeamExodus/external_strace,bnoordhuis/strace,TeamExodus/external_strace,bnoordhuis/strace,geekboxzone/lollipop_external_strace,Saruta/strace,android-ia/platform_external_strace,vrastogi/strace,cuviper/strace,TeamExodus/external_strace,geekboxzone/mmallow_external_strace,CyanogenMod/android_external_strace,Distrotech/strace,Yu-AndroidM/android_external_strace,CyanogenMod/android_external_strace,Infinitive-OS/platform_external_strace,Distrotech/strace,bigzz/strace_android,AOSP-YU/platform_external_strace,geekboxzone/mmallow_external_strace,bnoordhuis/strace,Yu-AndroidM/android_external_strace,bnoordhuis/strace,kapdop/android_external_strace,Saruta/strace,geofft/strace,xin3liang/platform_external_strace,kapdop/android_external_strace,android-ia/platform_external_strace,TeamExodus/external_strace,kapdop/android_external_strace,geekboxzone/lollipop_external_strace,bigzz/strace_android,android-ia/platform_external_strace,xin3liang/platform_external_strace,CyanogenMod/android_external_strace,geofft/strace,geekboxzone/mmallow_external_strace,MonkeyZZZZ/platform_external_strace,bigzz/strace_android