bionic: reimplement property area as hybrid trie/binary tree

bionic: reimplement property area as hybrid trie/binary tree

See the comments for an explanation of how properties are stored.

The trie structure is designed to scale better than the previous
array-based implementation.  Searching an array with n properties
required average O(n) string compares of the entire key; searching the
trie requires average O(log n) string compares of each token (substrings
between '.' characters).

Change-Id: I491305bc7aca59609abcd871a5f33d97f89ce714
Signed-off-by: Greg Hackmann <ghackmann@google.com>