R-app: fix Sequoia build

[Knapoc]

Description

R-app: fix Sequoia build

fixes the build on Sequoia until the upstream issue in R-macos/Mac-GUI#15 is resolved

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 15.0 24A335 arm64
Xcode 16.0 16A242d

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL in commit message?
• checked your Portfile with port lint --nitpick?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?
• checked that the Portfile's most important variants haven't been broken?

[macportsbot]

Notifying maintainers:
@i0ntempest for port R-app.
@kjellpk for port R-app.