arm, i386: use PTRACE_GETREGSET if available
arm, i386: use PTRACE_GETREGSET if available

* syscall.c [ARM || I386 || X86_64] (get_regset): New function.
(get_regs) [ARM || I386 || X86_64]: Use it.

jamel/strace-plus,kapdop/android_external_strace,vrastogi/strace,pgbovine/strace-plus,lizh06/strace-plus,CyanogenMod/android_external_strace,TeamExodus/external_strace,lizh06/strace-plus,geofft/strace,Distrotech/strace,xin3liang/platform_external_strace,YUPlayGodDev/platform_external_strace,pombredanne/strace,Saruta/strace,bnoordhuis/strace,android-ia/platform_external_strace,pombredanne/strace,geofft/strace,jamel/strace-plus,CyanogenMod/android_external_strace,geofft/strace,Infinitive-OS/platform_external_strace,YUPlayGodDev/platform_external_strace,Saruta/strace,Yu-AndroidM/android_external_strace,AOSP-YU/platform_external_strace,Yu-AndroidM/android_external_strace,geekboxzone/mmallow_external_strace,Infinitive-OS/platform_external_strace,Saruta/strace,cuviper/strace,xin3liang/platform_external_strace,YUPlayGodDev/platform_external_strace,Yu-AndroidM/android_external_strace,geekboxzone/lollipop_external_strace,Distrotech/strace,geofft/strace,jamel/strace-plus,TeamExodus/external_strace,pgbovine/strace-plus,kapdop/android_external_strace,geofft/strace,CyanogenMod/android_external_strace,android-ia/platform_external_strace,CyanogenMod/android_external_strace,bnoordhuis/strace,CyanogenMod/android_external_strace,lizh06/strace-plus,MonkeyZZZZ/platform_external_strace,gcode-mirror/strace-plus,YUPlayGodDev/platform_external_strace,DirtyUnicorns/android_external_strace,cuviper/strace,lkundrak/strace,vrastogi/strace,MonkeyZZZZ/platform_external_strace,geekboxzone/mmallow_external_strace,kapdop/android_external_strace,xin3liang/platform_external_strace,pombredanne/strace,geekboxzone/lollipop_external_strace,jamel/strace-plus,lkundrak/strace,bigzz/strace_android,Saruta/strace,android-ia/platform_external_strace,bnoordhuis/strace,kapdop/android_external_strace,android-ia/platform_external_strace,gcode-mirror/strace-plus,bigzz/strace_android,gcode-mirror/strace-plus,AOSP-YU/platform_external_strace,cuviper/strace,bigzz/strace_android,lizh06/strace-plus,TeamExodus/external_strace,Infinitive-OS/platform_external_strace,MonkeyZZZZ/platform_external_strace,Yu-AndroidM/android_external_strace,geekboxzone/lollipop_external_strace,DirtyUnicorns/android_external_strace,YUPlayGodDev/platform_external_strace,cuviper/strace,Distrotech/strace,cuviper/strace,pgbovine/strace-plus,bigzz/strace_android,Yu-AndroidM/android_external_strace,MonkeyZZZZ/platform_external_strace,Infinitive-OS/platform_external_strace,vrastogi/strace,vrastogi/strace,geekboxzone/lollipop_external_strace,bigzz/strace_android,AOSP-YU/platform_external_strace,jamel/strace-plus,TeamExodus/external_strace,AOSP-YU/platform_external_strace,gcode-mirror/strace-plus,lkundrak/strace,Saruta/strace,Distrotech/strace,TeamExodus/external_strace,pgbovine/strace-plus,geekboxzone/lollipop_external_strace,AOSP-YU/platform_external_strace,pombredanne/strace,lkundrak/strace,geekboxzone/mmallow_external_strace,geekboxzone/mmallow_external_strace,bnoordhuis/strace,android-ia/platform_external_strace,geekboxzone/mmallow_external_strace,pgbovine/strace-plus,DirtyUnicorns/android_external_strace,gcode-mirror/strace-plus,DirtyUnicorns/android_external_strace,Distrotech/strace,MonkeyZZZZ/platform_external_strace,vrastogi/strace,DirtyUnicorns/android_external_strace,xin3liang/platform_external_strace,kapdop/android_external_strace,lizh06/strace-plus,Infinitive-OS/platform_external_strace