Fix headers inclusion for system headers 

Merge back changes from stable-1.5

Fix headers inclusion for system headers

Add info about pmemcheck annotations in readme

Fix ambiguous comments in make_persistent array

Changes are applied to files that were created after stable-1.5

Implement property that allows to subtract an iterator from another

Change breaking literals rule in clang.format

test: fix includes and flags

Add Valgrind annotation support

Add pmreorder support

and add test program to check if pmemobj supports COW for pool opening.
COW for reorder tests is needed because if checker program does any recovery
(for example in pool::open) this is not logged and will not be reverted by
pmreorder. This results in unexpected state in proceding pmreorder steps
(expected state is initial pool, modified only by pmreorder)

and pmemcheck has proper version

Add ctl support

Fix typo in pmem::obj::array method description

Change SUPP_DIR to TEST_ROOT_DIR

add test iterators helpers

Add informations about type limitations to persistent_ptr

and use it to specify true.cmake location.
this variable points to the root test directory and can be used
to specify path also to other files (e.g. true.cmake)

and specify what is considered as UB by the standard.

Fix minor issues

Fix clang format detection

common: replace 'C' headers with equivalent 'C++' headers for C++ specific files

add next_pow_2 common helper function