Squashed 'libs/libhtp/' changes from d1c16de..f9763cd

f9763cd Improve coverage of the urlencoded parser.
821e58b Fix urlencoded parser getting confused about its keys and values. Add further defensive handling of NULL values. Improve tests.

git-subtree-dir: libs/libhtp
git-subtree-split: f9763cd2872e2a58f79deb2456025ca012430e71
Merge commit 'bd812b438c44146b091940aae4bd2278b5a943d2' into 0.7.x
Squashed 'libs/libhtp/' changes from f9763cd..9ff8285

9ff8285 Do not allow htp_tx_req_process_body_data() to be invoked with NULL data.
67b051a Add tests for a suspected crash. Could not replicate.

git-subtree-dir: libs/libhtp
git-subtree-split: 9ff8285ddf557186fb0d20927a7025fe08ee555d
Merge commit '87a1b88c01f1a5c649e0ad72945fffb1628188f1' into 0.7.x
State notify: Log and ignore empty body data
modhtp: Ignore empty body data