get_cpu() and get_platform_info() do not work correctly on PowerPC

[barracuda156]

Benchmarks run fine, however CPU and other system info are not picked:

> get_cpu()
$vendor_id
character(0)

$model_name
character(0)

$no_of_cores
[1] 2

> get_platform_info()
$OS.type
[1] "unix"

$file.sep
[1] "/"

$dynlib.ext
[1] ".so"

$GUI
[1] "X11"

$endian
[1] "big"

$pkgType
[1] "source"

$path.sep
[1] ":"

$r_arch
[1] ""

> get_r_version()
$platform
[1] "powerpc-apple-darwin10.0.0d2"

$arch
[1] "powerpc"

$os
[1] "darwin10.0.0d2"

$system
[1] "powerpc, darwin10.0.0d2"

$status
[1] ""

$major
[1] "4"

$minor
[1] "2.3"

$year
[1] "2023"

$month
[1] "03"

$day
[1] "15"

$`svn rev`
[1] "83980"

$language
[1] "R"

$version.string
[1] "R version 4.2.3 (2023-03-15)"

$nickname
[1] "Shortstop Beagle"