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/intrin/findnextfile.greg.c

@@ -19,12 +19,14 @@
 #include "libc/calls/internal.h"
 #include "libc/calls/strace.internal.h"
 #include "libc/intrin/describeflags.internal.h"
+#include "libc/nt/errors.h"
 #include "libc/nt/files.h"
 #include "libc/nt/memory.h"
+#include "libc/nt/runtime.h"
 #include "libc/nt/struct/win32finddata.h"
 #include "libc/nt/thunk/msabi.h"
 
-extern typeof(FindNextFile) *const __imp_FindNextFileW __msabi;
+__msabi extern typeof(FindNextFile) *const __imp_FindNextFileW;
 
 /**
  * Finds more files in directory.
@@ -45,8 +47,8 @@ textwindows bool32 FindNextFile(int64_t hFindFile,
         DescribeNtFileFlagsAndAttributes(out_lpFindFileData->dwFileAttributes),
         DescribeNtFiletypeFlags(out_lpFindFileData->dwFileType), ok);
   } else {
-    __winerr();
-    STRACE("FindNextFile(%ld, [n/a]) → %hhhd% m", hFindFile, ok);
+    if (GetLastError() != kNtErrorNoMoreFiles) __winerr();
+    STRACE("FindNextFile(%ld) → %hhhd% m", hFindFile, ok);
   }
   return ok;
 }