Fixed arc drawing bug for a non-whole number of degrees

[radarhere]

Resolves #4005

If the angle between the start and end of an arc is not a whole number

Pillow/src/libImaging/Draw.c

Lines 771 to 772 in 5a203b7

	ellipse(Imaging im, int x0, int y0, int x1, int y1,
	float start, float end, const void* ink_, int fill,

Pillow/src/libImaging/Draw.c

Line 778 in 5a203b7

int maxEdgeCount;

then simply combining the two floats is not correct.

Pillow/src/libImaging/Draw.c

Line 837 in 5a203b7

maxEdgeCount = end - start;

@cgohlke figured this out, and solves it by rounding up.