Elevate Windows production worthiness

- SQLite file locking now works on Windows
- SQLite will now use fdatasync() on non-Apple platforms
- Fix Ctrl-C handler on Windows to not crash with TLS
- Signals now work in multithreaded apps on Windows
- fcntl() will now accurately report EINVAL errors
- fcntl() now has excellent --strace logging
- Token bucket replenish now go 100x faster
- *NSYNC cancellations now work on Windows
- Support closefrom() on NetBSD

libc/intrin/describeopenflags.c

@@ -32,6 +32,7 @@ const char *(DescribeOpenFlags)(char buf[128], int x) {
   char *s;
   int i, n;
   struct DescribeFlags d[N];
+  if (x == -1) return "-1";
   // TODO(jart): unify DescribeFlags and MagnumStr data structures
   for (n = 0; kOpenFlags[n].x != MAGNUM_TERMINATOR; ++n) {
     if (n == N) notpossible;