detect GDB and disable tests

ref issue #469

Backport hash map erase fix to stable 1.8

Consider the following scenario (where A and B are in the same bucket):
thread 1:		thread 2:
find(acc1, A)
			erase(A)
find(acc2, B)

First, thread 1 takes lock on the bucket and then on element A.
Then, thread 2 takes a lock on the bucket and tries to lock element A
but it can't because thread 1 already locked it - this way thread 2 is blocked.
Next, thread 1 tries to lock the bucket but it can't because thread 2 holds it.
Neither thread can progress.

This patch fixes that by introducing the same algorithm as in lookup/insert.
When trying to lock element in erase we now spin in a loop doing try_acquire and
if we do not succeed after specified amount of time we drop bucket lock and try
whole operation again.

Merge stable 1.7 into stable 1.8

Fix overrding TEST_DIR variable

TEST_DIR is used to specify location of test artifacts. It can NOT
be overwritten.

Add missing pmdk-debuginfo rpms installation

Merge changes from stable-1.6

tests: remove unnecessary #include <libpmemobj.h>

Merge changes from stable-1.5

allocator: remove unnecessary #include <libpmemobj.h>

Including libpmemobj.h causes inclusion of all type macros
which are not needed by C++.

Including libpmemobj.h causes inclusion of all type macros
which are not needed by C++.

test: remove concurrent_hash_map_pmreorder_insert_erase_mt test

Multi-threaded tests cannot be run under pmreorder,
because pmreorder does not support multi-threaded tests.

Vs 2019 fixes

Update comment for pool::persist(persistent_ptr&)

Fix finding libpmem and libpmemobj in CMake

Functions modified in this patch do not modify the object so they should be
marked as const.

This fixes compilation on VS 2019.

to initialization list. Every const member (like table_ptr)
should be initialized this way. Failing to do so may result in compilation
error.

Generate the fatal error if any of the required files is not found.

Former description could have been misinterpreted. Persist
operation does not persist pointee but only a pointer - this
change makes that clear.

Ref: https://github.com/pmem/libpmemobj-cpp/issues/524

Implement rehash_bucket using a transaction

And use it for long running tests (concurrent hash map drd tests).