not NUL-terminated -> NUL-terminated
make path_has_protocol non static

We will use path_has_protocol outside block.c, so just make it public.

Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
qed_read_string to bdrv_read_string

Make qed_read_string function to a common interface, so move it to
block.c.

Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
rename