Fix btio.c compilation warning

This patch fixes a compilation warning regarding btio/btio.c. Actually
this warning seems a false positive by Ubuntu Natty GCC version. A new
bug on Ubuntu bug system was opened but if you do not want to wait until
it is analyzed, just apply this minor fix.

btio/btio.c: In function 'bt_io_get':
btio/btio.c:803:11: warning: 'flushable' may be used uninitialized in
this function
diff --git a/btio/btio.c b/btio/btio.c
index 6d71b90..a3cf38a 100644
--- a/btio/btio.c
+++ b/btio/btio.c
@@ -800,7 +800,7 @@
 	uint8_t dev_class[3];
 	uint16_t handle;
 	socklen_t len;
-	gboolean flushable;
+	gboolean flushable = FALSE;
 	len = sizeof(l2o);
 	memset(&l2o, 0, len);