Fixed ia bug that I introduced into the CTA command-line tool

when I modified it to read results back in a
"read until end of file" loop.

The bug was that instead of trying to read 1 KiB chunks of data
from the cta front-end, the chunk size was only 8 bytes (the size
of 64-bit pointer).  The calculation of the chunk size was
incorrectly:

   sizeof(buf - 1)

instead of:

   sizeof(buf) - 1

cmdline/CTACmdMain.cpp

@@ -161,7 +161,7 @@ int sendCommand(const int argc, const char **argv) {
       bytesRead = 0;
       char buf[1024];
       memset(buf, 0, sizeof(buf));
-      const XrdCl::XRootDStatus readStatus = xrootFile.Read(readOffset, sizeof(buf - 1), buf, bytesRead);
+      const XrdCl::XRootDStatus readStatus = xrootFile.Read(readOffset, sizeof(buf) - 1, buf, bytesRead);
       if(!readStatus.IsOK()) {
         throw std::runtime_error(std::string("Failed to read ") + cmdPath + ": " + readStatus.ToStr());
       }