Port mq_get() to MinGW.

test/src/mq.c

@@ -0,0 +1,27 @@
+#include "test/jemalloc_test.h"
+
+/*
+ * Sleep for approximately ns nanoseconds.  No lower *nor* upper bound on sleep
+ * time is guaranteed.
+ */
+void
+mq_nanosleep(unsigned ns)
+{
+
+	assert(ns <= 1000*1000*1000);
+
+#ifdef _WIN32
+	Sleep(ns / 1000);
+#else
+	struct timespec timeout;
+
+	if (ns < 1000*1000*1000) {
+		timeout.tv_sec = 0;
+		timeout.tv_nsec = ns;
+	} else {
+		timeout.tv_sec = 1;
+		timeout.tv_nsec = 0;
+	}
+	nanosleep(&timeout, NULL);
+#endif
+}