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/sock/select.internal.h

@@ -0,0 +1,13 @@
+#ifndef COSMOPOLITAN_LIBC_SOCK_SELECT_INTERNAL_H_
+#define COSMOPOLITAN_LIBC_SOCK_SELECT_INTERNAL_H_
+#include "libc/mem/alloca.h"
+#include "libc/sock/select.h"
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+const char *DescribeFdSet(char[100], ssize_t, int, fd_set *);
+#define DescribeFdSet(x, y, z) DescribeFdSet(alloca(100), x, y, z)
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_SOCK_SELECT_INTERNAL_H_ */