[update] update to upstream commit e15a2b9
Squashed 'qtmultimedia/' changes from fca1262..1c0cfdf

1c0cfdf Add changes-5.1.0 file
e25db62 Multimedia plugins now have a unique JSON metadata 'Keys' property.
16a775d Android: Fix for uncaught java exception.
ccc4138 Fix for url bug in the qmlvideo examples.

git-subtree-dir: qtmultimedia
git-subtree-split: 1c0cfdf408a398f4fe3efded775341b50106505d
Merge commit '8a920f8263158bba8a364ae1d26e6a1464cbf680'