fix_core_name: revert test code

test/bthread_butex_unittest.cpp

@@ -42,8 +42,6 @@ TEST(ButexTest, wait_on_already_timedout_butex) {
     *butex = 1;
     ASSERT_EQ(-1, bthread::butex_wait(butex, 1, &now));
     ASSERT_EQ(ETIMEDOUT, errno);
-    int* p = NULL;
-    *p = 0;
 }
 
 void* sleeper(void* arg) {

test/run_tests.sh

@@ -40,6 +40,7 @@ print_bt () {
     # find newest core file
     COREFILE=$(find . -name "core*" -type f -printf "%T@ %p\n" | sort -k 1 -n | cut -d' ' -f 2- | tail -n 1)
     if [ ! -z "$COREFILE" ]; then
+        >&2 echo "corefile=$COREFILE prog=$1"
         gdb -c "$COREFILE" $1 -ex "thread apply all bt" -ex "set pagination 0" -batch;
     fi
 }