apply: report input location in header parsing errors

apply: report input location in header parsing errors

Several header parsing errors in apply.c still report only line
numbers. When applying more than one input, that does not tell the
user which input the line belongs to.

Report the patch input location for these header parsing errors, and
update the related tests.

While touching parse_git_diff_header(), update the helper state to use
the current header line when reporting these errors.

Signed-off-by: Jialong Wang <jerrywang183@yahoo.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>