libuv: fixup SRC_URI

Add the trailing '.git' to git repo uri in SRC_URI then it could share
source code repo on premirror with grpc which uses libuv as a git
submodule with fixed revision.

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit cecdf616)
Signed-off-by: Steve Sakoman <steve@sakoman.com>