Please describe the problem:
GtkCellRendererProgress does not respond to changes in the xalign attribute.
Instead, it is always centered in the cell. I don't mind that the
GtkCellRendererProgress is by default centered, but it should be able to be set
to left-aligned or right-aligned if the user requests it.

Trouble code in GtkCellRendererProgress seems to be:

pos = (w - logical_rect.width)/2;

I'm using GTK+ binaries so I'm not able to modify this to work with xalign myself.

Steps to reproduce:
1. Create a GtkCellRendererProgress
2. Set its xalign attribute to 0.0 or 1.0
3. Add the GtkCellRendererProgress to the col and insert the col


Actual results:
Cell is always centered.

Expected results:
It should respond to the xalign attribute and move accordingly.

Does this happen every time?
yes

Other information: