E741 ambiguous variable name 'l'
Change 'l' to another variable in affected code.
Also had to set the latex_engine to 'xelatex' in doc/source/conf.py
in order to get past an openstackdocstheme change the broke the pdf
doc build.
Change-Id: Idd176e40ccf2a79832a5c99140bd30e5e1f9c0d8