Reduce use of parameterized productions in parser.
Reduce use of parameterized productions in parser.

Otherwise Happy 1.19.8 produces parsers that are extremely slow to
compile.

HIPERFIT/futhark,diku-dk/futhark,diku-dk/futhark,diku-dk/futhark,diku-dk/futhark,HIPERFIT/futhark,diku-dk/futhark,HIPERFIT/futhark