gtest: Hotfix to prevent download failure

gtest: Hotfix to prevent download failure

gtest-1.7.0.zip (md5=2d6ec8ccdf5c46b05ba54a9fd1d130d7) is gone from:
  https://googletest.googlecode.com/files/gtest-1.7.0.zip

So let's switch to a mirrored file:
  http://pkgs.fedoraproject.org/repo/pkgs/gtest/gtest-1.7.0.zip/2d6ec8ccdf5c46b05ba54a9fd1d130d7/gtest-1.7.0.zip

Note, now upstream project moved to:
  https://github.com/google/googletest/archive/release-1.7.0.zip

But archive structure is different (configure is missing),
 so a additional works are needed,
 maybe it worth to be done on latest release instead (1.8.0 ATM).

Change-Id: Ib1cf308fb2d3a15bdf69246cccfd379234bbce22
Bug: https://jira.iotivity.org/browse/IOT-820
Origin: https://gerrit.iotivity.org/gerrit/#/c/11119/
Signed-off-by: Philippe Coval <philippe.coval@osg.samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/11119
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jaehong Jo <jaehong.jo@samsung.com>
Reviewed-by: Jihun Ha <jihun.ha@samsung.com>
Reviewed-by: Jaewook Jung <jw0213.jung@samsung.com>
Reviewed-by: Uze Choi <uzchoi@samsung.com>