bootstrap:cprinter: nullable, nonnullable: avoiding an intermediate C var
bootstrap:cprinter: nullable, nonnullable: avoiding an intermediate C var

Such intermediate vars are fine with plain refs, but are not with crefs.
Instead we use #defines, which are also likely less costly for the
C compiler.

nanocritical/n,nanocritical/n,nanocritical/n,nanocritical/n