(draw_petrucci_g_clef): Resolve all self intersections.

(draw_petrucci_g_clef): Resolve all self intersections.

The algorithm used by mf2pt1 to compute the correct orientation of an
outline may fail if there are self intersections.  For simple outlines
which don't intersect other outlines this is automatically fixed by
fontforge, but more complicated shapes need the correct orientation.

Note that the recently released metapost 1.0 has an improved version
of the `turningnumber' primitive which gives reliable results in
all cases (including paths with self intersections); however, mf2pt1
hasn't been updated yet to use it.