common: add three checks to cstyle
examples: add Intel license to four source files
Merge pull request #15 from ldorau/examples-add-Intel-license

examples: add Intel license to four files
common: fix cstyle checking

Make cstyle check benchmark directory and correct cstyle errors
in this directory.
Merge pull request #16 from ldorau/common-fix-cstyle-checking

common: fix cstyle checking
Merge pull request #17 from ldorau/common-add-three-checks-to-cstyle

common: add three checks to cstyle
doc: add instructions for contributing

Fixes: pmem/issues#2
benchmarks: add Intel license to two source files
test: update PHONY targets in two Makefiles
Merge pull request #18 from ldorau/benchmarks-add-Intel-license

benchmarks: add Intel license to two source files
Merge pull request #19 from ldorau/test-update-PHONY-targets

test: update PHONY targets in two Makefiles
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.