Merge branch 'js/async-thread'

* js/async-thread:
  fast-import: die_nicely() back to vsnprintf (reverts part of ebaa79f)
  Enable threaded async procedures whenever pthreads is available
  Dying in an async procedure should only exit the thread, not the process.
  Reimplement async procedures using pthreads
  Windows: more pthreads functions
  Fix signature of fcntl() compatibility dummy
  Make report() from usage.c public as vreportf() and use it.
  Modernize t5530-upload-pack-error.

Conflicts:
	http-backend.c

compat/mingw.h

@@ -89,7 +89,7 @@ static inline int getuid()
 { return 1; }
 static inline struct passwd *getpwnam(const char *name)
 { return NULL; }
-static inline int fcntl(int fd, int cmd, long arg)
+static inline int fcntl(int fd, int cmd, ...)
 {
 	if (cmd == F_GETFD || cmd == F_SETFD)
 		return 0;