Windows: Fix a few more benign compiler warnings

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>
diff --git a/libusb/os/windows_common.c b/libusb/os/windows_common.c
index f25c340..119ed49 100644
--- a/libusb/os/windows_common.c
+++ b/libusb/os/windows_common.c
@@ -114,7 +114,7 @@
 
 	filename_start = library_path + length;
 	// Append '\' + name + ".dll" + NUL
-	length += 1 + strlen(name) + 4 + 1;
+	length += 1 + (UINT)strlen(name) + 4 + 1;
 	if (length >= (UINT)sizeof(library_path)) {
 		usbi_err(ctx, "program assertion failed - library path buffer overflow");
 		return NULL;
diff --git a/libusb/os/windows_winusb.c b/libusb/os/windows_winusb.c
index 7d47323..f291b8e 100644
--- a/libusb/os/windows_winusb.c
+++ b/libusb/os/windows_winusb.c
@@ -994,6 +994,9 @@
 		config_desc_length = ROOT_HUB_FS_CONFIG_DESC_LENGTH;
 		ep_interval = 0xff;	// 255ms
 		break;
+	default:			// Impossible, buts keeps compiler happy
+		usbi_err(ctx, "program assertion failed - unknown root hub speed");
+		return LIBUSB_ERROR_INVALID_PARAM;
 	}
 
 	if (speed >= LIBUSB_SPEED_SUPER) {
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index 18701f1..411b5f9 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11579
+#define LIBUSB_NANO 11580