libmeminfo: Report VMA flags in showmap report

Add VMA flags into showmap report so that we can distinguish different
sections of an executable or a library.

Bug: 138148041
Test: showmap -v <PID>
Change-Id: Ic1a13accbea447548c75a0c54d750280e40c6de8
Signed-off-by: Suren Baghdasaryan <surenb@google.com>