The documented syntax for most GCC options that take magic keywords is of the
form @option{-ffoo=@var{magic}}, with the various literal values for
@var{magic} listed in the option description. There are a number, though,
that list the keyword choices in the syntax, but with two different markup
conventions. This patch changes the ones that wrap the whole keyword list in
@var, like -fvtable-verify, to use the same markup convention as the others,
like -Wsuggest-attribute, which use the regular option/code font for the
keywords but set off the syntactic delimiters "[", "|", and "]" in Roman
font.. @var is supposed to be for metasyntactic variables and seems
inappropriate for literal keywords, so I think it's less correct than the
other convention.