Remove abort from FcCompareSize.

There doesn't appear to be a good reason to abort when 'v1' has type
FcTypeRange. If there does turn out to be a good reason for this then it
should be better documented and the code for handling this case removed.
At worst it seems -1 should be returned as it is for other unknown
types. It is possible this is left over debug code from the initial
1 file changed