Fix the libunwind version of prof_backtrace().
Fix the libunwind version of prof_backtrace().

Fix the libunwind version of prof_backtrace() to set the backtrace depth
for all possible code paths.  This fixes the zero-length backtrace
problem when using libunwind.

wespelee/jemalloc,yy-nm/jemalloc,AndroidExternal/jemalloc,vashstorm/jemalloc,wqfish/jemalloc,sudosurootdev/external_jemalloc,percona/jemalloc-debian,vashstorm/jemalloc,garoose/jemalloc,flyfeifan/jemalloc,geekboxzone/lollipop_external_jemalloc,cpeterso/jemalloc,vashstorm/jemalloc,xin3liang/platform_external_jemalloc,lvfeng1130/jemalloc,geekboxzone/lollipop_external_jemalloc,TeamExodus/external_jemalloc,glandium/jemalloc,geekboxzone/mmallow_external_jemalloc,xin3liang/platform_external_jemalloc,percona/jemalloc-debian,wespelee/jemalloc,leebaok/jemalloc-4.2.1-readcode,lilothar/jemalloc,xin3liang/platform_external_jemalloc,lilothar/jemalloc,AndroidExternal/jemalloc,dcreager/jemalloc,geekboxzone/mmallow_external_jemalloc,Snaipe/jemalloc,geekboxzone/lollipop_external_jemalloc,kmiku7/jemalloc,lilothar/jemalloc,VRToxin/android_external_jemalloc,awreece/jemalloc,lvfeng1130/jemalloc,AndroidExternal/jemalloc,wfxiang08/jemalloc,8l/jemalloc,shekkbuilder/jemalloc,tempbottle/jemalloc,garoose/jemalloc,8l/jemalloc,wespelee/jemalloc,jemalloc/jemalloc-cmake,dxq-git/jemalloc,TeamExodus/external_jemalloc,wqfish/jemalloc,kmiku7/jemalloc,wfxiang08/jemalloc,CyanogenMod/android_external_jemalloc,geekboxzone/lollipop_external_jemalloc,flyfeifan/jemalloc,Dmitry-Me/jemalloc,percona/jemalloc-debian,TeamExodus/external_jemalloc,yy-nm/jemalloc,awreece/jemalloc,android-ia/platform_external_jemalloc,CMRemix/android_external_jemalloc,lvfeng1130/jemalloc,CyanogenMod/android_external_jemalloc,dxq-git/jemalloc,xin3liang/platform_external_jemalloc,CyanogenMod/android_external_jemalloc,wqfish/jemalloc,Snaipe/jemalloc,sudosurootdev/external_jemalloc,yy-nm/jemalloc,tempbottle/jemalloc,lvfeng1130/jemalloc,8l/jemalloc,VRToxin/android_external_jemalloc,tempbottle/jemalloc,TeamExodus/external_jemalloc,lilothar/jemalloc,glandium/jemalloc,cpeterso/jemalloc,android-ia/platform_external_jemalloc,sudosurootdev/external_jemalloc,CMRemix/android_external_jemalloc,Dmitry-Me/jemalloc,8l/jemalloc,splbio/jemalloc,Snaipe/jemalloc,garoose/jemalloc,cpeterso/jemalloc,AndroidExternal/jemalloc,geekboxzone/mmallow_external_jemalloc,jemalloc/jemalloc-cmake,flyfeifan/jemalloc,kmiku7/jemalloc,wespelee/jemalloc,dxq-git/jemalloc,wfxiang08/jemalloc,CMRemix/android_external_jemalloc,ahmetmircik/jemalloc,ahmetmircik/jemalloc,glandium/jemalloc,Dmitry-Me/jemalloc,VRToxin/android_external_jemalloc,kmiku7/jemalloc,Dmitry-Me/jemalloc,shekkbuilder/jemalloc,tempbottle/jemalloc,Snaipe/jemalloc,ahmetmircik/jemalloc,wqfish/jemalloc,splbio/jemalloc,splbio/jemalloc,geekboxzone/mmallow_external_jemalloc,jemalloc/jemalloc-cmake,glandium/jemalloc,yy-nm/jemalloc,vashstorm/jemalloc,wqfish/jemalloc,CMRemix/android_external_jemalloc,leebaok/jemalloc-4.2.1-readcode,android-ia/platform_external_jemalloc,dxq-git/jemalloc,dcreager/jemalloc,shekkbuilder/jemalloc,jemalloc/jemalloc-cmake,awreece/jemalloc,leebaok/jemalloc-4.2.1-readcode,flyfeifan/jemalloc,wfxiang08/jemalloc,shekkbuilder/jemalloc,sudosurootdev/external_jemalloc,cpeterso/jemalloc,android-ia/platform_external_jemalloc,ahmetmircik/jemalloc,awreece/jemalloc,dcreager/jemalloc,garoose/jemalloc,percona/jemalloc-debian,leebaok/jemalloc-4.2.1-readcode,CyanogenMod/android_external_jemalloc,VRToxin/android_external_jemalloc