[libcxxabi] Fix the test case committed in r303175.
[libcxxabi] Fix the test case committed in r303175.

Free the __cxa_exception object allocated with __cxa_allocate_exception.

This is an attempt to fix this asan bot:

http://lab.llvm.org:8011/builders/libcxx-libcxxabi-x86_64-linux-ubuntu-asan/builds/560

git-svn-id: 6a9f6578bdee8d959f0ed58970538b4ab6004734@303194 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/libcxxabi,llvm-mirror/libcxxabi,llvm-mirror/libcxxabi,llvm-mirror/libcxxabi,llvm-mirror/libcxxabi