luna-sysmgr-common: bump SRCREV

Includes the following changes:

 87c7dc6 Add some animation related classes from luna-sysmgr
 ec24478 Merge remote-tracking branch 'upstream/master' into webOS-ports/master
 e6ef21b Add "number of cached WebKit UpdateAtlases" setting
 a0da38c Add settings for tuning WebKit tiled backing store

Signed-off-by: Simon Busch <morphis@gravedo.de>