emlog: new package

[Thomas:
 - update to the latest github version, which has a number of
   fixes/improvements compared to the latest tag.
 - add a patch to fix the build of the kernel module with recent
   kernel versions (>= 3.19).
 - use $(INSTALL) -D with a full destination path.
 - rewrap Config.in help text, lines were too long.]

Signed-off-by: Joris Lijssens <joris.lijssens@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>