Link to libcef.so in the current directory.

Link to libcef.so in the current directory.

Newer CEF hard-codes that icudtl.dat _must_ be in the same directory
as libcef.so, but the release tarballs have a different structure,
so this fails. This should be fine on installs, but it won't work
for running Nageru from the build directory. Search for the library
in the local directory instead, where we have a symlink. This makes
the build rpath point to ., which makes sure icudtl.dat is picked up
from the other symlink.