CellArea: Fix documentation of typedef SlotForeachAlloc

* gtk/src/cellarea.hg: SlotForeachAlloc: An extra '>' in the docs trapped
doxygen 1.8.4 in an infinite loop.
Update .gitignore files

* build/.gitignore:
* .gitignore: Ignore files generated by automake 1.13 and 'make check'.