[R] Fix build flags on Raspberry Pi

[asfimport]

Reporter: Nicola Crane / @thisisnic
Assignee: Nicola Crane / @thisisnic

PRs and other links:

• GitHub Pull Request #10404

_{Note: This issue was originally created as ARROW-12876. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
Issue resolved by pull request 10404
#10404