Windows: Implement getwd() & make ls() public.

os/os_win.v

@@ -4,11 +4,22 @@
 
 module os
 
-fn ls(path string) []string {
+pub fn ls(path string) []string {
 	mut res := []string
 	return res
 }
 
+pub fn getwd() string {
+	mut buffer := malloc(512)
+	
+	buffer = C._getcwd(0, 0)
+	// A NULL return value indicates an error
+	if isnil(buffer) {
+		return ''
+	}
+	return string(buffer)
+}
+
 const (
 	FILE_ATTRIBUTE_DIRECTORY = 16
 )
@@ -22,11 +33,6 @@ fn chdir(path string) {
 	C._chdir(path.cstr())
 }
 
-fn getwd() string {
-	panic('getwd() not impl')
-	return ''
-}
-
 fn log(s string) {
 }