common: fix array behaviour when its size is zero.

This patch fixes 2 things:
 - Double braced initialization of scalar types is not allowed in C++
   so previous version, where underlying type for zero sized array
   was pointer prevented proper zero-sized array initlizatation.
   (Only some compilers complained about this)
 - Standard states that begin() and end() should return some unique value,
   now it is done by returning address of the array itself. To achive that
   alignment of zero-sized array is equal to alignment of type its holding.
   This approach is also taken by libstdc++.

Limit test execution & dump stack trace when they fail.

workaround for old gcc version issue

Check if "inline" aggregate initialization works for array
class members. Use double braces initialization as a workaround.

test: add support for matching memcheck logs

Provide support for matching memcheck and pmemcheck output files.
Match file should follow pattern:
<testname>_<testcase_nr>_<tracer>.err.match

obj: fix pmem::obj::v<> to match new changes

Required due to the pmemobj_volatile API change.

tests: match logs automatically on test finish

common: use coverage flag to group metrics

Introduce pmem::obj::array

Imported from https://github.com/llvm-mirror/libcxx/commit/88f5d7a38bf379d2772a7c0b064b680d6eaea4dc

common: fix doc update script

tests: skip pmemcheck tests if pmemcheck is not found

Using git commit -a only staged modified or deleted files but new files were ommited.

common: fix some warnings on windows

reported by MSVC.

Update clang format

Add aggregate initialization support

which fixes unused variable warning in release build.