Fix for extra string width padding in ui_text_icon_width, causing labels in right-aligned layouts show an annoying gap. If the layout is right-aligned, make the text button align right as well, so text is drawn at the right side of the alloted rect.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55463 954f8c5b-7b00-dc11-b283-0030488c597c