disable drd test

disable concurrent_map_insert_reopen drd tests due to intermittent
failres (missing annotation, see issue https://github.com/pmem/libpmemobj-cpp/issues/770)

Fix sporadic DRD issue in concurrent skip list

concurrent_map: fix windows compilation

Fix Doxygen warnings in the concurrent_skip_list_impl.hpp

concurrent_map fixes

otherwise thread 11 and 12 might not start when we try to switch
to them in gdb script.

_size is a volatile variable and does not have to be flushed.
pmemcheck complained about missing flush in pmemkv tests.

Fix misleading warning message

add issue templates for GitHub interface

concurrent_map: fix windows compilation

On older MSVC versions sizeof(member) is not allowed in definition
of non-static members. Fix this by adding decltype().

Concurrent map data structure

Make pmem::allocator::allocate() throw exceptions in case of bad
allocation.
Make pmem::allocator::construct() throw exception if it is called
outside of transaction.

Implementation is based on concurrent skip list.
Ref:
https://www.cs.tau.ac.il/~shanir/nir-pubs-web/Papers/OPODIS2006-BA.pdf

tests: report error if binary is not built

Merge stable 1.9 into master

Cleanup CI files

based on PMDK's commit 96db274c7, added:
- '-j' param to coverity command (make)
- necessary vars for coverity script (used for Travis CI)
- Coverity certificate download
- skip for forked repos

And fix cases where binary is not built but test is added.

Add libcxx tests for map

Added mockups in CMakeFiles
Files copied from:
https://github.com/llvm-mirror/libcxx/commit/78d6a7767

and do minor cleanup in docker scripts.

- add skip arguments/flags for PMDK and Valgrind builds
- move env variable settings to the top of the files

concurrent_hash_map: fix free_data()

Setting ptr to null after calling delete_persistent is required to
ensure proper recovery.

bump Valgrind version to newest pmem-3.15

If free_data() was called twice this led to assertion failure and
possible double free.

This patch skips freeing data when tls_ptr is already nullptr.

Apply vcpkg patch for pmdk (stable 1.9)