[Rd] Buig in bin/R script (PR#9375)

[gml4410 at ggr.co.uk]

Full_Name: Gordon Lack
Version: 2.4.0
OS: OSF1 v5.1
Submission from: (NULL) (198.28.92.5)


Changes to the bin/R front-end interlude script at 2.4.0 (cf: 2.2.0) have broken
R on (Dec/Compaq/HP) OSF1.

There are 3 occurrences of "${@}", but this is the incorrect syntax for adding
$@, as on older Bourne shells this will add an empty (but present) parameter. 
The result is that the build fails while attempting to add in the Recommended
libraries because "ARGUMENT '' __ignored__" end up on the gcc command line.

The fix is to edit src/scripts//R.sh.in to use the correct, original Bourne
shell syntax:

 ${1+"$@"}

(ie: if there is a $1, add quoted $@, else do nothing) on the THREE occurrences
of "${@}"