column: don't ignore space-char separators at begin of the line

column: don't ignore space-char separators at begin of the line

Non-space separator:

	$ echo -e ",col1,col2\nrow,1,2" | column -t -s ","  --table-columns A,B,C
	A    B     C
	     col1  col2
	row  1     2

Space-char (\t) separator:

	$ echo -e "\tcol1\tcol2\nrow\t1\t2" | column -t -s "$(echo -e '\t')"  --table-columns A,B,C
	A     B     C
	col1  col2
	row   1     2

Fixed version:

	$ echo -e "\tcol1\tcol2\nrow\t1\t2" | column -t -s "$(echo -e '\t')"  --table-columns A,B,C
	A    B     C
	     col1  col2
	row  1     2

Addresses: https://github.com/karelzak/util-linux/issues/575
Signed-off-by: Karel Zak <kzak@redhat.com>