Return the path to the directory containing keops source
files that are shipped with rkeops installation.
get_src_dir(pkg = "rkeops")path to the corresponding directory.
name (string) of the R package, default is "rkeops".
Ghislain Durif
This path is generaly something like
/path/to/R_package_install/rkeops/include.
Note: when running tests in the development project keops without
installing rkeops, for consistency reason, the function returns
/path/to/keops/rkeops/inst/include (because the content of
rkeops/inst/include is copied to rkeops/include at installation).