ARM: tests/Gtest-dyn1.c fixes.
ARM: tests/Gtest-dyn1.c fixes.

Define an appropriate fdesc struct and its corresponding accessors that take
care of the thumb marker on ARM. Call the __clear_cache built-in instead of
flush_cache if the GNU compiler is used.

Signed-off-by: Ken Werner <ae36958ca69fd249ce813d415cd5831a3fb45335@linaro.org>

dropbox/libunwind,igprof/libunwind,geekboxzone/mmallow_external_libunwind,jrmuizel/libunwind,ehsan/libunwind,fdoray/libunwind,frida/libunwind,jrmuizel/libunwind,pathscale/libunwind,evaautomation/libunwind,fillexen/libunwind,zeldin/platform_external_libunwind,0xlab/0xdroid-external_libunwind,tkelman/libunwind,Keno/libunwind,Chilledheart/libunwind,DroidSim/platform_external_libunwind,SyndicateRogue/libunwind,geekboxzone/mmallow_external_libunwind,0xlab/0xdroid-external_libunwind,cloudius-systems/libunwind,vegard/libunwind,vegard/libunwind,joyent/libunwind,rogwfu/libunwind,CyanogenMod/android_external_libunwind,Keno/libunwind,vtjnash/libunwind,Chilledheart/libunwind,project-zerus/libunwind,geekboxzone/mmallow_external_libunwind,DroidSim/platform_external_libunwind,unkadoug/libunwind,androidarmv6/android_external_libunwind,rntz/libunwind,libunwind/libunwind,maltek/platform_external_libunwind,ehsan/libunwind,fdoray/libunwind,krytarowski/libunwind,wdv4758h/libunwind,lat/libunwind,maltek/platform_external_libunwind,SyndicateRogue/libunwind,adsharma/libunwind,bo-on-software/libunwind,unkadoug/libunwind,fillexen/libunwind,cloudius-systems/libunwind,frida/libunwind,dagar/libunwind,atanasyan/libunwind,pathscale/libunwind,tony/libunwind,tkelman/libunwind,dreal-deps/libunwind,android-ia/platform_external_libunwind,olibc/libunwind,wdv4758h/libunwind,DroidSim/platform_external_libunwind,androidarmv6/android_external_libunwind,vegard/libunwind,dreal-deps/libunwind,cms-externals/libunwind,frida/libunwind,androidarmv6/android_external_libunwind,project-zerus/libunwind,fdoray/libunwind,lat/libunwind,atanasyan/libunwind,tkelman/libunwind,tony/libunwind,jrmuizel/libunwind,rantala/libunwind,evaautomation/libunwind,cloudius-systems/libunwind,0xlab/0xdroid-external_libunwind,rantala/libunwind,rogwfu/libunwind,tony/libunwind,rntz/libunwind,yuyichao/libunwind,djwatson/libunwind,rogwfu/libunwind,project-zerus/libunwind,adsharma/libunwind,geekboxzone/lollipop_external_libunwind,igprof/libunwind,tronical/libunwind,mpercy/libunwind,yuyichao/libunwind,tronical/libunwind,djwatson/libunwind,wdv4758h/libunwind,igprof/libunwind,unkadoug/libunwind,SyndicateRogue/libunwind,Chilledheart/libunwind,atanasyan/libunwind-android,krytarowski/libunwind,atanasyan/libunwind-android,djwatson/libunwind,dropbox/libunwind,mpercy/libunwind,zeldin/platform_external_libunwind,zliu2014/libunwind-tilegx,mpercy/libunwind,zeldin/platform_external_libunwind,adsharma/libunwind,vtjnash/libunwind,joyent/libunwind,olibc/libunwind,cms-externals/libunwind,android-ia/platform_external_libunwind,CyanogenMod/android_external_libunwind,dagar/libunwind,atanasyan/libunwind,olibc/libunwind,zliu2014/libunwind-tilegx,CyanogenMod/android_external_libunwind,maltek/platform_external_libunwind,martyone/libunwind,fillexen/libunwind,martyone/libunwind,bo-on-software/libunwind,yuyichao/libunwind,geekboxzone/lollipop_external_libunwind,krytarowski/libunwind,zliu2014/libunwind-tilegx,rntz/libunwind,lat/libunwind,android-ia/platform_external_libunwind,pathscale/libunwind,libunwind/libunwind,martyone/libunwind,evaautomation/libunwind,ehsan/libunwind,dropbox/libunwind,vtjnash/libunwind,bo-on-software/libunwind,dagar/libunwind,rantala/libunwind,atanasyan/libunwind-android,tronical/libunwind,Keno/libunwind,geekboxzone/lollipop_external_libunwind,joyent/libunwind,libunwind/libunwind,cms-externals/libunwind,dreal-deps/libunwind