tizen: Remove extlibs git history for gbs export
tizen: Remove extlibs git history for gbs export

Note this is executed just before gbs build,
to allow prepare scripts to use git if needed.

Note:
I noticed an old version of mbedtls is cached on jenkins.

Bug: https://jira.iotivity.org/browse/IOT-1745
Change-Id: I6d28421e2778ca5f6815a450678df3a8e08033e3
Signed-off-by: Philippe Coval <ff46fec9739d31cce915aabcc3a7a2c00eee4d6c@osg.samsung.com>
Origin: https://gerrit.iotivity.org/gerrit/#/c/20345/
Reviewed-on: https://gerrit.iotivity.org/gerrit/20345
Tested-by: jenkins-iotivity <d95b56ce41a2e1ac4cecdd398defd7414407cc08@iotivity.org>
Reviewed-by: Jaehong Jo <69db334b3f87f30654728856fde276b43c835fe5@samsung.com>
Reviewed-by: Dave Thaler <8a98d0850f57b73c42d096f8f8b11e2d5522d554@microsoft.com>
Reviewed-by: Ziran Sun <3baa2a3e3c6d96dba4b6f1736d53815847db9a07@samsung.com>
(cherry picked from commit 5fb0d3438b27afb6a1284bba5e4898c2daed6202)
Reviewed-on: https://gerrit.iotivity.org/gerrit/20343

rzr/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,iotivity/iotivity