lstm unit test segfault on CI

[TejashShah]

../bin/test_lstm --float --batch-size 32 --seq-len 3 --vector-len 128 --hidden-size 128 --num-<layers 1 --no-hx --no-dhy --use-dropout 0 --in-mode 0 --bias-mode 1 --dir-mode 0 --algo-mode <0 --batch-seq 32 32 32 
Warning: verify cache failed, rerunning cpu.
FAILED: 0.00418963
Max diff: 0.172064
Mismatch at 2: 0.00870884 != 0.00870884
./bin/MIOpenDriver rnn -n 32,32,32 -m lstm  -k 3 -H 128 -W 128 -l 1 -F 0  -r 0 -b 1 -p 0
inputMode: 0 biasMode: 1 dirMode: 0
hz: 128 batch_n: 96 seqLength: 3 inputLen: 128 numLayers: 1 useDropout: 0
Backward Weights LSTM: 
Memory access fault by GPU node-8 (Agent handle: 0x563e6e15e340) on address <0x7f498334a000. Reason: Page not present or supervisor privilege.
Aborted (core dumped)
test/CMakeFiles/test_lstm_extra.dir/build.make:57: recipe for target 'test/CMakeFiles</test_lstm_extra' failed

The CI job where the failure was reported is here.

[atamazov]

Yes, this happens from time to time.

Let's also add into scope of this ticket the full-blown fix of the following commit introduced in #240:

• c71697a [test_lstm] The "Forward Inference LSTM" sub-test is disabled.

[atamazov]

@TejashShah let's use > for quoting text and ```...``` for quoting logs.

[daniellowell]

Do not seem like a real issue. Please reopen if needed.

[ce1adon]

It's probably related with the verification cache, which is disabled here PR #448 .