enhance PyTorch easyblock to also capture tests failing with signal

[Flamefire]

(created using eb --new-pr)

This now captures test like:

	distributed/rpc/test_tensorpipe_agent failed!
	test_fx failed! Received signal: SIGSEGV

See https://github.com/pytorch/pytorch/blob/8be853025cb9fe7dd165924957b01984b46b9459/test/run_test.py#L915

[boegel]

Test report by @boegel

Overview of tested easyconfigs (in order)

• SUCCESS PyTorch-1.11.0-foss-2021a-CUDA-11.3.1.eb

Build succeeded for 1 out of 1 (1 easyconfigs in total)
node3900.accelgor.os - Linux RHEL 8.4, x86_64, AMD EPYC 7413 24-Core Processor (zen3), 1 x NVIDIA NVIDIA A100-SXM4-80GB, 510.73.08, Python 3.6.8
See https://gist.github.com/57645bd053424943389adbd0d8e168fc for a full test report.

[boegel]

List of failing tests is still reported correctly:

WARNING: 3 tests (out of 89226) failed:
* distributed/fsdp/test_fsdp_input
* distributed/test_c10d_gloo
* test_autograd

[boegel]

lgtm