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/runtime/runtime.h

@@ -93,6 +93,7 @@ void __printargs(const char *);
 int ftrace_install(void);
 int ftrace_enabled(int);
 int strace_enabled(int);
+bool strace_enter(void);
 void _bt(const char *, ...);
 void __print_maps(void);
 long _GetMaxFd(void);
@@ -141,6 +142,15 @@ long __get_minsigstksz(void) pureconst;
 void __get_main_stack(void **, size_t *, int *);
 long __get_safe_size(long, long);
 char *__get_tmpdir(void);
+__funline int __trace_disabled(int x) {
+  return 0;
+}
+#ifndef FTRACE
+#define ftrace_enabled __trace_disabled
+#endif
+#ifndef SYSDEBUG
+#define strace_enabled __trace_disabled
+#endif
 #endif /* _COSMO_SOURCE */
 
 COSMOPOLITAN_C_END_