[LibFuzzer] Split the fuzzer-oom.test into two tests.

This is necessary because the existing fuzzer-oom.test was Linux
specific due to its use of __sanitizer_print_memory_profile() which
is only available on Linux right now and so the test would fail on OSX.

Differential Revision: http://reviews.llvm.org/D20977

llvm-svn: 272061