version: extend get_uname_info() to hide system details

version: extend get_uname_info() to hide system details

Currently, get_uname_info() function provides the full OS information.
In a following commit, we will need it to provide only the OS name.

Let's extend it to accept a "full" flag that makes it switch between
providing full OS information and providing only the OS name.

We may need to refactor this function in the future if an
`osVersion.format` is added.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>