.mailmap: Add entries for inconsistent users
.mailmap: Add entries for inconsistent users

Before this commit:

$ git shortlog -se
  ...
    38  Brandon Philips <brandon.philips@coreos.com>
     1  Brandon Philips <brandon@ifup.org>
  ...
     3  Doug Davis <dug@us.ibm.com>
     1  Doug Davis <duglin@users.noreply.github.com>
  ...
     3  Sergiusz Urbaniak <sergiusz.urbaniak@gmail.com>
    15  Sergiusz Urbaniak <sur@coreos.com>
  ...
     3  xiekeyang <keyang.xie@gmail.com>
    18  xiekeyang <xiekeyang@huawei.com>

Signed-off-by: zhouhao <f577ade201aa03d612c19915a089dc6084d45cd9@cn.fujitsu.com>

opencontainers/image-tools,opencontainers/image-tools