font-patcher: Handle center aligned and overlapped glyphs

[why]
When we have glyphs that need to be patched in with overlap into a
NerdFontPropo font, the advance width is not correct(ed).

[how]
I am not sure why specifically left and right alignment has been
mentioned, but of course center alignment also needs to be handled.

Overlap can be positive or negative, that does not matter here.

Signed-off-by: Fini Jastrow <ulf.fini.jastrow@desy.de>

font-patcher

@@ -1624,7 +1624,7 @@ class font_patcher:
                 else:
                     width = sym_dim['width']
                 # If we have overlap we need to subtract that to keep/get negative bearings
-                if overlap and (sym_attr['align'] == 'l' or sym_attr['align'] == 'r'):
+                if overlap:
                     width -= overlap_width
                 # Fontforge handles the width change like this:
                 # - Keep existing left_side_bearing