Bug G02 rotation fix

[mumme74]

CW move G02 was drawing CCW when R calulation made J go to zero

Example that shows this:

G17 ( Plane X,Y )
G21 ( Millimeter )
G91 ( Incremental )
G40 ( Cancel radius compensation )
G92 X0 Z0 ( Offset coordinate system )
G00 X100 Y100 Z-49 (1mm from workpiece)
G01 Z-4 F10

(ERROR: CCW as J goes to 0)
G02 X-60 R30

G01 Y10
(Works! CCW as J does not reach 0)
G02 X-59.999 R30

(Go Home)
G00 Z4
G28 (Go home)
M30