Enabled core dump on Linux, and print stack trace on failure.

src/ci/docker/run.sh

@@ -99,6 +99,7 @@ objdir=$root_dir/obj
 
 mkdir -p $HOME/.cargo
 mkdir -p $objdir/tmp
+mkdir $objdir/cores
 
 args=
 if [ "$SCCACHE_BUCKET" != "" ]; then

src/ci/run.sh

@@ -24,6 +24,11 @@ if [ "$NO_CHANGE_USER" = "" ]; then
   fi
 fi
 
+# only enable core dump on Linux
+if [ -f /proc/sys/kernel/core_pattern ]; then
+  ulimit -c unlimited
+fi
+
 ci_dir=`cd $(dirname $0) && pwd`
 source "$ci_dir/shared.sh"