test: 添加 Bug6

playground/BugFarm/Bug6/Main.snow

@@ -0,0 +1,13 @@
+module: Main
+    import: os
+    globals:
+        declare sum: int = 123
+    function: main
+        parameter:
+        return_type: int
+        body:
+            os.print(sum)
+            return 0
+        end body
+    end function
+end module

playground/BugFarm/Bug6/OS.snow

@@ -0,0 +1,11 @@
+module: os
+    import: os
+    function: print
+        parameter:
+            declare i1: int
+        return_type: void
+        body:
+            syscall("PRINT",i1)
+        end body
+    end function
+end module