LdFlags and RcppLdFlags return the required flags and
options for the system linker. This allows portable use of
LdFlags is commonly called from the files Makevars (or
Makevars.win) rather than in an interactive session.
LdFlags(static=staticLinking())
RcppLdFlags(static=staticLinking())staticLinking()
function which defaults to FALSE on Linux, and TRUE
if the operating system is different from Linux.vignette("Rcpp-introduction").