config: teach git_config_source to remember its scope
There are many situations where the scope of a config command is known
beforehand, such as passing of '--local', '--file', etc. to an
invocation of git config. However, this information is lost when moving
from builtin/config.c to /config.c. This historically hasn't been a big
deal, but to prepare for the upcoming --show-scope option we teach
git_config_source to keep track of the source and the config machinery
to use that information to set current_parsing_scope appropriately.
Signed-off-by: Matthew Rogers <mattr94@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>