atk/atk.symbols: Add Symbols for AtkTableCell
atk/atk.symbols: Add Symbols for AtkTableCell

... so that they will also be exported in Windows builds

Distrotech/atk,Distrotech/atk,GNOME/at-spi2-core,GNOME/at-spi2-core,Distrotech/atk,GNOME/at-spi2-core