[R-pkg-team] s.d.o/r-pkg-team/r-cran-rmpfr please remove

[Steffen Möller]

Hello,

I apologize to have started the packaging of that multiple-precision
library independently. I'll eventually prepare a patch to the
prepare_R_package script to check if the URL for the nascent package's
repository is already existing. Anyway, that repository is in no good
shape and long outdated. Please just remove it for me.

Many thanks
Steffen