l10n: git.pot: v2.15.0 round 1 (68 new, 36 removed)

Generate po/git.pot from commit d35688d ("Prepare for -rc1",
2017-10-07) for git v2.15.0 l10n round 1.

Signed-off-by: Jiang Xin <[email protected]>

Author: jiangxin