Improve synchronization

- Fix bugs in kDos2Errno definition
- malloc() should now be thread safe
- Fix bug in rollup.com header generator
- Fix open(O_APPEND) on the New Technology
- Fix select() on the New Technology and test it
- Work towards refactoring i/o for thread safety
- Socket reads and writes on NT now poll for signals
- Work towards i/o completion ports on the New Technology
- Make read() and write() intermittently check for signals
- Blinkenlights keyboard i/o so much better on NT w/ poll()
- You can now poll() files and sockets at the same time on NT
- Fix bug in appendr() that manifests with dlmalloc footers off

libc/calls/wait4-nt.c

@@ -67,7 +67,7 @@ static textwindows int sys_wait4_nt_impl(int pid, int *opt_out_wstatus,
       if (!__isfdopen(pid) &&
           (handle = OpenProcess(kNtSynchronize | kNtProcessQueryInformation,
                                 true, pid))) {
-        if ((pid = __reservefd()) != -1) {
+        if ((pid = __reservefd(-1)) != -1) {
           g_fds.p[pid].kind = kFdProcess;
           g_fds.p[pid].handle = handle;
           g_fds.p[pid].flags = O_CLOEXEC;
@@ -111,6 +111,8 @@ static textwindows int sys_wait4_nt_impl(int pid, int *opt_out_wstatus,
     }
     if (opt_out_rusage) {
       bzero(opt_out_rusage, sizeof(*opt_out_rusage));
+      bzero(&memcount, sizeof(memcount));
+      memcount.cb = sizeof(struct NtProcessMemoryCountersEx);
       if (GetProcessMemoryInfo(handles[i], &memcount, sizeof(memcount))) {
         opt_out_rusage->ru_maxrss = memcount.PeakWorkingSetSize / 1024;
         opt_out_rusage->ru_majflt = memcount.PageFaultCount;