vmem: fix pages purging for file mapped memory

Madvise system call with MADV_DONTNEED does _not_
fill pages with zeroes when memory is mapped to underlying file.
See madvice(2) for details.

pages_purge() function was saying that memory region has been zeroed
after calling madvice with MADV_DONTNEED - which was _not_ true.
This was causing an assertion fault because the page's meta-data was
invalid.

To fix this issue:
Return proper value in pages_purge() in order to set proper flag in
internal metadata. For file mapped memory pages_purge() does not
zero-fill pages. Only pool with id number 0 is anonymously mapped - pages are
filled with zeros.
Merge pull request #2 from plebioda/fix-unzeroed-pages-assert

vmem: fix pages purging for file mapped memory
log: create multi-threaded benchmark
Merge pull request #24 from mjgrabowski/nvml-mjgrabows-log-benchmark

Nvml mjgrabows log benchmark
vmem: vmem_pool_create_in_region() address alignment up to Pagesize

-Update page protection in vmem_pool_create_in_region()
-Update man page
-Update Unit Tests.
Merge pull request #26 from spawlows/vmem-pool-create-in-region-addrs-allig

vmem: vmem_pool_create_in_region() address alignment up to Pagesize
blk: fix offsets in BTT Info header

- store backup of BTT Info header on valid position
- do not store offset to next arena if remaining size if less than
  BTT_MIN_SIZE
- fix offset and count checking in nswrite and nsread
Merge pull request #27 from plebioda/fix-btt-info-header-offsets

blk: fix offsets in BTT Info header
vmem: extend test vmem_stats to check multiple pools
blk: pad flog entries to cache line boundaries
vmem: fix vmem_freespace, vmem_valgrind unit tests

-Fix sporadical assert failures in vmem_freespace
-Change message about skipped tests in UT vmem_valgrind
Merge pull request #29 from spawlows/vmem-fix-unstable-tests

vmem: fix vmem_freespace, vmem_valgrind unit tests
Merge pull request #30 from spawlows/vmem-stats-test-multiple-pools

vmem: extend test vmem_stats to check multiple pools
vmem: fix aligned address to page in benchmark
Merge pull request #32 from spawlows/vmem-benchmark-fix-aligned-to-page

vmem: fix aligned address to page in benchmark
btt: use mutex for map, not spin lock
blk: organize map_locks by cache line
blk: use 2*ncpu for maxlane based on perf analysis
Merge pull request #31 from andyrudoff/blk_flog_pad

blk: pad flog entries and deal with map entries in CL-sizes
common: add rules to run jemalloc tests

- add rules to run jemalloc tests separately
- run debug and nondebug jemalloc tests
- run jemalloc tests before vmem tests