LibPDF/CFF: Clear stack after "endchar" commands

Both type 1 and type 2 spec tell us to do this.

I haven't observed a difference from this, but I noticed it in the
spec while I was touching this code. Probably good to do what the
spec tells us to do.

Userland/Libraries/LibPDF/Fonts/Type1FontProgram.cpp

@@ -663,6 +663,7 @@ PDFErrorOr<Type1FontProgram::Glyph> Type1FontProgram::parse_glyph(ReadonlyBytes
                     }
                     path.close();
                 }
+                state.sp = 0;
                 break;
             }