Include system RAM size in usage report

cmd/syncthing/memsize_windows.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"encoding/binary"
+	"syscall"
+	"unsafe"
+)
+
+var (
+	kernel32, _             = syscall.LoadLibrary("kernel32.dll")
+	globalMemoryStatusEx, _ = syscall.GetProcAddress(kernel32, "GlobalMemoryStatusEx")
+)
+
+func memorySize() (uint64, error) {
+	var memoryStatusEx [64]byte
+	binary.LittleEndian.PutUint32(memoryStatusEx[:], 64)
+	p := uintptr(unsafe.Pointer(&memoryStatusEx[0]))
+
+	ret, _, callErr := syscall.Syscall(uintptr(globalMemoryStatusEx), 1, p, 0, 0)
+	if ret == 0 {
+		return 0, callErr
+	}
+
+	return binary.LittleEndian.Uint64(memoryStatusEx[8:]), nil
+}