[Rd] StringFromInteger made private in r38652

[Seth Falcon]

Hi,

In commit 38652, StringFromInteger (among others) was removed from R's
public API.  I've just come across a Bioconductor package, RdbiPgSql,
that uses this function.

Is there an alternative that is in the public API?  If not, it would
be nice to be able to reuse these sorts of helper functions
(StringFrom*) instead of reimplementing them for each package.

+ seth