signal相关数据结构&代码结构优化 (#84)

* 解决由于spinlock.h中包含preempt_enable()带来的循环include问题

* new: 初步实现signal的数据结构

.vscode/settings.json

@@ -150,11 +150,11 @@
         "cfs.h": "c",
         "err.h": "c",
         "rtc.h": "c",
-        "wait_queue_head.h": "c",
         "list.h": "c",
         "compiler.h": "c",
         "completion.h": "c",
-        "fat32.h": "c"
+        "fat32.h": "c",
+        "irqflags.h": "c"
     },
     "C_Cpp.errorSquiggles": "Enabled",
     "esbonio.sphinx.confDir": "",