Bison 3.0 was released in 2013, and the current Debian stable (buster)
has version 3.3.2.

* m4/bison.m4: Remove -Wno-precedence and -Wno-empty-rule, keep
-Wno-deprecated just to protect from future deprecation warnings that
would be interpreted as errors.
* spot/parseaut/parseaut.yy, spot/parsetl/parsetl.yy: Use %empty
rules, prefer %precedence over %nonassoc, update %error-versbose and
%name-prefix to their more modern equivalent.
* spot/misc/trival.hh (maybe): Mark this function as noexcept to
please the compiler while compiling the parsers.