bug#40371: [R7RS] Guile does not accept library name parts that are non-negative exact integers

An R7RS library name consists of parts, where each part is either a symbol
or a non-negative exact integer. Guile doesn't support the latter ones.

This is unfortunate as the implementation of a SRFI NNN is usually
delivered in form of a library named (srfi NNN).

When this is corrected, for interoperability, it would be great if Guile
offers the included SRFIs not only under the name (srfi srfi-NNN) but also
under (srfi NNN).

Thanks,

Marc