linux/syscall.h: make subcall decoding configuration more readable
linux/syscall.h: make subcall decoding configuration more readable

* linux/syscall.h: Inverse and sort the subcall ifdef,
add a comment why subcall decoding support is not enabled
on some architectures.

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