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

third_party/musl/lockf.c

@@ -25,13 +25,13 @@
 │  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                      │
 │                                                                              │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "third_party/musl/lockf.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/struct/flock.h"
 #include "libc/calls/weirdtypes.h"
 #include "libc/errno.h"
 #include "libc/sysv/consts/f.h"
 #include "libc/sysv/errfuns.h"
-#include "third_party/musl/lockf.h"
 
 asm(".ident\t\"\\n\\n\
 Musl libc (MIT License)\\n\
@@ -68,3 +68,5 @@ int lockf(int fd, int op, off_t size)
 	}
 	return einval();
 }
+
+__weak_reference(lockf, lockf64);