Some implementations of sscanf do not handle a space before a trailing %n
properly.
As an example, MSVC's does this for the second insatnce in this patch, for
an input of "0x3:c0=c1:c1=c0":
1) Match the final "c0" or "c1".
2) Realize it's at the end of the string.
3) Check for %n.
4) There is no %n, but a space instead.
5) Leave 'len' unitilialized.
So, move it out of the sscanf format strings, and call skip_spaces instead.
This bug does not affect skip_spaces since %n is the first and only formatting
string.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
