check for panic exit status directly

Since rust-lang/rust#52197, ICEs will fail with exit status 101.
Compilation successes and failures will return 0 and 1, respectively.

Fixes rust-lang#143.

test.sh

@@ -4,8 +4,9 @@ for f in src/*
 do
   [[ -f $f ]] || continue;
   echo "Testing $f:"
-  # Compile the code, and if it passes exit with error code
-  if rustc "$f" > /dev/null 2>&1; then
+  # Compile the code, and if it exits without a panic, exit with error code
+  rustc "$f" > /dev/null 2>&1
+  if [ "$?" == 101 ]; then
     exit 1
   fi
 done