meson: Fix build on macOS

Previously, Meson failed to run on macOS. This was because a value that should
have been an array of strings was instead a single string.
4 jobs for fix-meson-on-macos in 19 minutes and 5 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #270449
fedora-autotools

00:11:37

passed #270450
fedora-meson

00:08:51

manual #270452
win32 allowed to fail manual
msys2-mingw32-autotools
passed #270451
win32
msys2-mingw32-meson

00:19:05