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/calls/overlapped.internal.h

@@ -0,0 +1,25 @@
+#ifndef COSMOPOLITAN_LIBC_CALLS_OVERLAPPED_INTERNAL_H_
+#define COSMOPOLITAN_LIBC_CALLS_OVERLAPPED_INTERNAL_H_
+#include "libc/nt/struct/overlapped.h"
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+#define overlapped_cleanup_push(handle, overlap)                     \
+  {                                                                  \
+    struct OverlappedCleanup overlapped_cleanup = {handle, overlap}; \
+    pthread_cleanup_push(overlapped_cleanup_callback, &overlapped_cleanup);
+
+#define overlapped_cleanup_pop() \
+  pthread_cleanup_pop(false);    \
+  }
+
+struct OverlappedCleanup {
+  int64_t handle;
+  struct NtOverlapped *overlap;
+};
+
+void overlapped_cleanup_callback(void *);
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_CALLS_OVERLAPPED_INTERNAL_H_ */