nproc: Use Core::System::hardware_concurrency()

This is significantly simpler than parsing JSON and using the cpuinfo
array length.

This also has the side effect of making that command work on AArch64
and RISC-V, since ProcessorInfo is not implemented on those
architectures yet.

Author: spholz

Userland/Utilities/nproc.cpp

@@ -11,13 +11,9 @@
 
 ErrorOr<int> serenity_main(Main::Arguments)
 {
-    TRY(Core::System::pledge("stdio rpath"));
-    auto file = TRY(Core::File::open("/sys/kernel/cpuinfo"sv, Core::File::OpenMode::Read));
+    TRY(Core::System::pledge("stdio"));
 
-    auto buffer = TRY(file->read_until_eof());
-    auto json = TRY(JsonValue::from_string(buffer));
-    auto const& cpuinfo_array = json.as_array();
-    outln("{}", cpuinfo_array.size());
+    outln("{}", Core::System::hardware_concurrency());
 
     return 0;
 }