Add more raw system calls to redbean

We now have execve, setitimer, sigaction, sigsuspend, and sigprocmask.

tool/net/luacheck.h

@@ -0,0 +1,22 @@
+#ifndef COSMOPOLITAN_TOOL_NET_LUACHECK_H_
+#define COSMOPOLITAN_TOOL_NET_LUACHECK_H_
+#include "libc/log/log.h"
+#include "libc/mem/mem.h"
+#include "third_party/lua/cosmo.h"
+#include "third_party/lua/lua.h"
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+#define AssertLuaStackIsEmpty(L)                  \
+  do {                                            \
+    if (lua_gettop(L)) {                          \
+      char *s = LuaFormatStack(L);                \
+      WARNF("lua stack should be empty!\n%s", s); \
+      free(s);                                    \
+      lua_settop(L, 0);                           \
+    }                                             \
+  } while (0)
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_TOOL_NET_LUACHECK_H_ */