Many of our documents have babel-specific preamble code. By putting
this code in a \@ifpackageloaded{babel}{}{} conditional, XeTeX and
LuaTeX compilation with polyglossia now works. This fixes some
LuaTeX tests that were broken by edd37de8 and also allows us to
uninvert some XeTeX tests.
Note that in some of the files although the preambles were fixed to
allow for polyglossia, they still do not compile without errors:
es/Math.lyx
es/Customization.lyx
de/Customization.lyx
Similar fixes might be desired in other manuals but these at least
fix regressions in the tests.
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