Enable testing on devdax

[lukaszstolarczuk]

Please provide a reproduction of the bug:

run tests on devdax path, e.g.:

pmemkv/build # cmake .. -DTEST_DIR=/dev/dax0.0
# make tests
# ctest -R cmap__put_get_remove__default_0_none --output-on-failure

How often bug is revealed:

always

Actual behavior:

Test #11: cmap__put_get_remove__default_0_none ............................................***Failed    0.10 sec
Error creating directory "/dev/dax0.0/cmap__put_get_remove__default_0_none".
-- Executing:  /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove cmap;{"path":"/dev/dax0.0/cmap__put_get_remove__default_0_none/testfile"}
-- Test cmap__put_get_remove__default_0_none:
-- Stdout:

Signal: Aborted, backtrace:
0: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (test_sighandler+0x32) [0x55ffdca73b30]
1: /lib/x86_64-linux-gnu/libc.so.6 (killpg+0x40) [0x7fef5f8f224f]
2: /lib/x86_64-linux-gnu/libc.so.6 (gsignal+0xcb) [0x7fef5f8f218b]
3: /lib/x86_64-linux-gnu/libc.so.6 (abort+0x12b) [0x7fef5f8d1859]
4: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (UT_FATAL+0xd1) [0x55ffdca4ec5b]
5: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (_Z13INITIALIZE_KVNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEON4pmem2kv6configE+0xd5) [0x55ffdca4ef22]
6: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (_ZL16run_engine_testsNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES4_St6vectorISt8functionIFvRN4pmem2kv2dbEEESaISC_EE+0x90) [0x55ffdca4f7f7]
7: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (_ZL4testiPPc+0x2fb) [0x55ffdca6f3e9]
8: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (_ZZ4mainENKUlvE_clEv+0x2a) [0x55ffdca6f56e]
9: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (_ZNSt17_Function_handlerIFvvEZ4mainEUlvE_E9_M_invokeERKSt9_Any_data+0x24) [0x55ffdca6fb98]
10: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (_ZNKSt8functionIFvvEEclEv+0x36) [0x55ffdca7121a]
11: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (_ZL8run_testSt8functionIFvvEE+0x1e) [0x55ffdca4ed61]
12: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (main+0x52) [0x55ffdca6f5c3]
13: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf3) [0x7fef5f8d30b3]
14: /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove (_start+0x2e) [0x55ffdca4eace]


-- Stderr:
/home/jenkins-slave/workspace/pmemkv_linux/pmemkv/tests/common/unittest.hpp:178 INITIALIZE_KV - assertion failure:
 current_status (0x1) == pmem::kv::status::OK (0x0),
errormsg: [pmemkv_open] Failed opening pool: os_access "/dev/dax0.0/cmap__put_get_remove__default_0_none/testfile": Not a directory

CMake Error at /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/tests/helpers.cmake:178 (message):
   /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/build/tests/put_get_remove cmap;{"path":"/dev/dax0.0/cmap__put_get_remove__default_0_none/testfile"} failed: 134
Call Stack (most recent call first):
  /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/tests/helpers.cmake:218 (execute_common)
  /home/jenkins-slave/workspace/pmemkv_linux/pmemkv/tests/engines/pmemobj_based/default.cmake:16 (execute)

Expected behavior:

test passes