events_posix: Remove unnecessary and incorrect assertion

Thomas Chiantia reports that the POSIX events abstraction is failing
periodically because of incorrect assertion logic. Remove it as there is
another (correct) check further into the function that will serve check
the intended condition.

Closes #775

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>
diff --git a/libusb/os/events_posix.c b/libusb/os/events_posix.c
index 952ea5f..b74189b 100644
--- a/libusb/os/events_posix.c
+++ b/libusb/os/events_posix.c
@@ -254,7 +254,6 @@
 	}
 #endif
 
-	assert(num_ready > 0);
 	if (!num_ready)
 		goto done;
 
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index a0044a0..829e7a0 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11550
+#define LIBUSB_NANO 11551