gh-152433: Windows: implement os.cpu_count() for UWP

Author: thexai

Modules/posixmodule.c

@@ -15990,7 +15990,9 @@ os_cpu_count_impl(PyObject *module)
 # ifdef MS_WINDOWS_DESKTOP
     ncpu = GetActiveProcessorCount(ALL_PROCESSOR_GROUPS);
 # else
-    ncpu = 0;
+    SYSTEM_INFO sysinfo;
+    GetSystemInfo(&sysinfo);
+    ncpu = sysinfo.dwNumberOfProcessors;
 # endif
 
 #elif defined(__hpux)