Fix display of compound glyphs that employ simple transforms

Fix display of compound glyphs that employ simple transforms

* src/sfnt.c (sfnt_transform_coordinates): Always compute an
affine transform matrix except if no scale is provided at all.
Unconditionally apply x_off and y_off.
(sfnt_decompose_compound_glyph): Delete arguments OF_X and
OFF_Y.  Apply component offsets after writing simple glyph
contours.
(sfnt_decompose_glyph): Modify for new calling convention.
(sfnt_transform_f26dot6): Modify analogously to
sfnt_decompose_compound_glyph.  Also correct anchor offset
computation to scale the unscaled component anchor coordinates
by the interpreter scale.
(sfnt_interpret_compound_glyph_1): Also modify for new calling
convention.
* src/sfnt.h (struct sfnt_compound_glyph_component): <u>: Make
scale fields signed.