Make improvements

- Improved async signal safety of read() particularly for longjmp()
- Started adding cancel cleanup handlers for locks / etc on Windows
- Make /dev/tty work better particularly for uses like `foo | less`
- Eagerly read console input into a linked list, so poll can signal
- Fix some libc definitional bugs, which configure scripts detected

libc/mem/wcsdup.c

@@ -25,6 +25,6 @@
  */
 wchar_t *wcsdup(const wchar_t *s) {
   size_t len = wcslen(s);
-  char *s2 = malloc((len + 1) * sizeof(wchar_t));
-  return s2 ? memcpy(s2, s, (len + 1) * sizeof(wchar_t)) : NULL;
+  wchar_t *s2 = malloc((len + 1) * sizeof(wchar_t));
+  return s2 ? wmemcpy(s2, s, len + 1) : NULL;
 }