Backup ( *~ ) files in R 2.9.2 distribution (PR#13914)

The R-2.9.2.tar.gz file, when unpacked, contains a small number of files
ending with an "~" -- usually backup files, which should probably not
find their way into an actual release:

schutz at sib-pc45:~/R/upstream/R-2.9.2$ find . -name \*~
./src/library/base/R/eval.R~
./src/library/base/man/expand.grid.Rd~
./src/library/base/man/with.Rd~
./src/library/graphics/R/rect.R~
./src/library/stats/R/mlm.R~
./src/library/utils/R/de.R~
./src/library/utils/man/combn.Rd~
./src/library/stats4/R/mle.R~
./src/library/stats4/man/profile-methods.Rd~

Fr?d?ric