ARROW-6415: [R] Remove usage of R CMD config CXXCPP
ARROW-6415: [R] Remove usage of R CMD config CXXCPP

Closes #5266 from nealrichardson/cxxcpp and squashes the following commits:

e9c931c1a <Neal Richardson> Stop using deprecated R CMD config CXXCPP, per CRAN request

Authored-by: Neal Richardson <beb59f0141269d2d04e73d0dcc1967b64ba87e13@gmail.com>
Signed-off-by: Sutou Kouhei <73218711cdd5d5c30ac66da3cc4d9d9204caf34b@clear-code.com>

apache/arrow,cpcloud/arrow,cpcloud/arrow,wesm/arrow,apache/arrow,cpcloud/arrow,wesm/arrow,renesugar/arrow,apache/arrow,wesm/arrow,apache/arrow,xhochy/arrow,wesm/arrow,renesugar/arrow,wesm/arrow,cpcloud/arrow,apache/arrow,laurentgo/arrow,icexelloss/arrow,cpcloud/arrow,icexelloss/arrow,laurentgo/arrow,renesugar/arrow,apache/arrow,renesugar/arrow,xhochy/arrow,wesm/arrow,renesugar/arrow,renesugar/arrow,wesm/arrow,apache/arrow,wesm/arrow,xhochy/arrow,cpcloud/arrow,xhochy/arrow,kou/arrow,laurentgo/arrow,icexelloss/arrow,apache/arrow,kou/arrow,kou/arrow,xhochy/arrow,cpcloud/arrow,icexelloss/arrow,xhochy/arrow,apache/arrow,icexelloss/arrow,laurentgo/arrow,kou/arrow,icexelloss/arrow,apache/arrow,kou/arrow,laurentgo/arrow,xhochy/arrow,renesugar/arrow,kou/arrow,xhochy/arrow,laurentgo/arrow,wesm/arrow,apache/arrow,cpcloud/arrow,icexelloss/arrow,icexelloss/arrow,kou/arrow,laurentgo/arrow,laurentgo/arrow,xhochy/arrow,kou/arrow,kou/arrow,icexelloss/arrow,wesm/arrow,laurentgo/arrow,kou/arrow,kou/arrow,icexelloss/arrow,cpcloud/arrow,apache/arrow,laurentgo/arrow,laurentgo/arrow,xhochy/arrow,xhochy/arrow,apache/arrow,icexelloss/arrow,kou/arrow,renesugar/arrow,wesm/arrow,laurentgo/arrow,wesm/arrow,cpcloud/arrow,renesugar/arrow,icexelloss/arrow,cpcloud/arrow,laurentgo/arrow,xhochy/arrow,cpcloud/arrow,wesm/arrow,xhochy/arrow,cpcloud/arrow,renesugar/arrow,kou/arrow,laurentgo/arrow,cpcloud/arrow,xhochy/arrow,xhochy/arrow,laurentgo/arrow,renesugar/arrow,icexelloss/arrow,apache/arrow,kou/arrow,wesm/arrow,renesugar/arrow,renesugar/arrow,renesugar/arrow,icexelloss/arrow,renesugar/arrow